diff --git a/Cargo.lock b/Cargo.lock
index cb25eb92be7..807e86917fe 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2762,8 +2762,7 @@ dependencies = [
 [[package]]
 name = "ethereum_ssz"
 version = "0.5.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d3627f83d8b87b432a5fad9934b4565260722a141a2c40f371f8080adec9425"
+source = "git+https://github.com/macladson/ethereum_ssz?branch=stable-container#2c85edeaa76bd78189a5eab1b8fbc50a325fc4aa"
 dependencies = [
  "ethereum-types 0.14.1",
  "itertools 0.10.5",
@@ -2773,12 +2772,12 @@ dependencies = [
 [[package]]
 name = "ethereum_ssz_derive"
 version = "0.5.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8eccd5378ec34a07edd3d9b48088cbc63309d0367d14ba10b0cdb1d1791080ea"
+source = "git+https://github.com/macladson/ethereum_ssz?branch=stable-container#2c85edeaa76bd78189a5eab1b8fbc50a325fc4aa"
 dependencies = [
  "darling 0.13.4",
  "proc-macro2",
  "quote",
+ "ssz_types",
  "syn 1.0.109",
 ]
 
@@ -5392,8 +5391,7 @@ dependencies = [
 [[package]]
 name = "milhouse"
 version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3826d3602a3674b07e080ce1982350e454ec253d73f156bd927ac1b652293f4d"
+source = "git+https://github.com/macladson/milhouse?branch=stable-container#31a44cccd2bddf4a026a715c09b2c12dca279697"
 dependencies = [
  "arbitrary",
  "derivative",
@@ -8030,8 +8028,7 @@ dependencies = [
 [[package]]
 name = "ssz_types"
 version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "625b20de2d4b3891e6972f4ce5061cb11bd52b3479270c4b177c134b571194a9"
+source = "git+https://github.com/macladson/ssz_types?branch=stable-container#0e10833105369f265e1ab6b2b2b5775904592a6d"
 dependencies = [
  "arbitrary",
  "derivative",
@@ -8853,8 +8850,7 @@ dependencies = [
 [[package]]
 name = "tree_hash"
 version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "134d6b24a5b829f30b5ee7de05ba7384557f5f6b00e29409cdf2392f93201bfa"
+source = "git+https://github.com/macladson/tree_hash?branch=stable-container#a7a21200be47993f52479783cb13333e5dd5b0d9"
 dependencies = [
  "ethereum-types 0.14.1",
  "ethereum_hashing",
@@ -8864,11 +8860,12 @@ dependencies = [
 [[package]]
 name = "tree_hash_derive"
 version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ce7bccc538359a213436af7bc95804bdbf1c2a21d80e22953cbe9e096837ff1"
+source = "git+https://github.com/macladson/tree_hash?branch=stable-container#a7a21200be47993f52479783cb13333e5dd5b0d9"
 dependencies = [
  "darling 0.13.4",
+ "proc-macro2",
  "quote",
+ "ssz_types",
  "syn 1.0.109",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index c696163387b..2fee340ed21 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -121,8 +121,8 @@ error-chain = "0.12"
 ethereum-types = "0.14"
 ethereum_hashing = "0.6.0"
 ethereum_serde_utils = "0.5.2"
-ethereum_ssz = "0.5"
-ethereum_ssz_derive = "0.5"
+ethereum_ssz = { git = "https://github.com/macladson/ethereum_ssz", branch = "stable-container" }
+ethereum_ssz_derive = { git = "https://github.com/macladson/ethereum_ssz", branch = "stable-container" }
 ethers-core = "1"
 ethers-providers = { version = "1", default-features = false }
 exit-future = "0.2"
@@ -137,7 +137,7 @@ libsecp256k1 = "0.7"
 log = "0.4"
 lru = "0.12"
 maplit = "1"
-milhouse = "0.1"
+milhouse = { git = "https://github.com/macladson/milhouse", branch = "stable-container" }
 num_cpus = "1"
 parking_lot = "0.12"
 paste = "1"
@@ -163,7 +163,7 @@ slog-term = "2"
 sloggers = { version = "2", features = ["json"] }
 smallvec = { version = "1.11.2", features = ["arbitrary"] }
 snap = "1"
-ssz_types = "0.6"
+ssz_types = { git = "https://github.com/macladson/ssz_types", branch = "stable-container" }
 strum = { version = "0.24", features = ["derive"] }
 superstruct = "0.8"
 syn = "1"
@@ -177,8 +177,8 @@ tracing-appender = "0.2"
 tracing-core = "0.1"
 tracing-log = "0.2"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
-tree_hash = "0.6"
-tree_hash_derive = "0.6"
+tree_hash = { git = "https://github.com/macladson/tree_hash", branch = "stable-container" }
+tree_hash_derive = { git = "https://github.com/macladson/tree_hash", branch = "stable-container" }
 url = "2"
 uuid = { version = "0.8", features = ["serde", "v4"] }
 warp = { version = "0.3.7", default-features = false, features = ["tls"] }
diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 9d744003360..e70bdd531e4 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -3446,7 +3446,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         {
             let mut slashable_cache = self.observed_slashable.write();
             for header in blobs
-                .into_iter()
+                .iter()
                 .filter_map(|b| b.as_ref().map(|b| b.signed_block_header.clone()))
                 .unique()
             {
diff --git a/beacon_node/beacon_chain/src/data_availability_checker/overflow_lru_cache.rs b/beacon_node/beacon_chain/src/data_availability_checker/overflow_lru_cache.rs
index 4863982b552..7d9ac5e9dc2 100644
--- a/beacon_node/beacon_chain/src/data_availability_checker/overflow_lru_cache.rs
+++ b/beacon_node/beacon_chain/src/data_availability_checker/overflow_lru_cache.rs
@@ -272,7 +272,7 @@ impl<E: EthSpec> PendingComponents<E> {
             BlockImportRequirement::AllBlobs => {
                 let num_blobs_expected = diet_executed_block.num_blobs_expected();
                 let Some(verified_blobs) = verified_blobs
-                    .into_iter()
+                    .iter()
                     .cloned()
                     .map(|b| b.map(|b| b.to_blob()))
                     .take(num_blobs_expected)
diff --git a/consensus/types/src/attestation.rs b/consensus/types/src/attestation.rs
index b8aa2560329..54aa01d39f8 100644
--- a/consensus/types/src/attestation.rs
+++ b/consensus/types/src/attestation.rs
@@ -5,7 +5,10 @@ use derivative::Derivative;
 use safe_arith::ArithError;
 use serde::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
-use ssz_types::BitVector;
+use ssz_types::{
+    typenum::{self, Unsigned},
+    BitVector,
+};
 use std::hash::{Hash, Hasher};
 use superstruct::superstruct;
 use test_random_derive::TestRandom;
@@ -51,6 +54,10 @@ impl From<ssz_types::Error> for Error {
         serde(bound = "E: EthSpec", deny_unknown_fields),
         arbitrary(bound = "E: EthSpec"),
     ),
+    specific_variant_attributes(Electra(tree_hash(
+        struct_behaviour = "profile",
+        max_fields = "typenum::U8"
+    ))),
     ref_attributes(derive(TreeHash), tree_hash(enum_behaviour = "transparent")),
     cast_error(ty = "Error", expr = "Error::IncorrectStateVariant"),
     partial_getter_error(ty = "Error", expr = "Error::IncorrectStateVariant")
diff --git a/consensus/types/src/attester_slashing.rs b/consensus/types/src/attester_slashing.rs
index f6aa654d445..f9a35357f0c 100644
--- a/consensus/types/src/attester_slashing.rs
+++ b/consensus/types/src/attester_slashing.rs
@@ -6,6 +6,10 @@ use derivative::Derivative;
 use rand::{Rng, RngCore};
 use serde::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
+use ssz_types::{
+    typenum::{self, Unsigned},
+    BitVector,
+};
 use superstruct::superstruct;
 use test_random_derive::TestRandom;
 use tree_hash_derive::TreeHash;
@@ -29,6 +33,10 @@ use tree_hash_derive::TreeHash;
         serde(bound = "E: EthSpec"),
         arbitrary(bound = "E: EthSpec")
     ),
+    specific_variant_attributes(Electra(tree_hash(
+        struct_behaviour = "profile",
+        max_fields = "typenum::U8"
+    ))),
     ref_attributes(derive(Debug))
 )]
 #[derive(
diff --git a/consensus/types/src/beacon_block_body.rs b/consensus/types/src/beacon_block_body.rs
index 305ef105445..dfaff2fada1 100644
--- a/consensus/types/src/beacon_block_body.rs
+++ b/consensus/types/src/beacon_block_body.rs
@@ -57,7 +57,10 @@ pub const BLOB_KZG_COMMITMENTS_INDEX: usize = 11;
         Bellatrix(metastruct(mappings(beacon_block_body_bellatrix_fields(groups(fields))))),
         Capella(metastruct(mappings(beacon_block_body_capella_fields(groups(fields))))),
         Deneb(metastruct(mappings(beacon_block_body_deneb_fields(groups(fields))))),
-        Electra(metastruct(mappings(beacon_block_body_electra_fields(groups(fields))))),
+        Electra(
+            metastruct(mappings(beacon_block_body_electra_fields(groups(fields)))),
+            tree_hash(struct_behaviour = "profile", max_fields = "typenum::U64"),
+        ),
     ),
     cast_error(ty = "Error", expr = "Error::IncorrectStateVariant"),
     partial_getter_error(ty = "Error", expr = "Error::IncorrectStateVariant")
diff --git a/consensus/types/src/beacon_state.rs b/consensus/types/src/beacon_state.rs
index b8ebe101205..28353d2d009 100644
--- a/consensus/types/src/beacon_state.rs
+++ b/consensus/types/src/beacon_state.rs
@@ -13,6 +13,10 @@ use safe_arith::{ArithError, SafeArith};
 use serde::{Deserialize, Serialize};
 use ssz::{ssz_encode, Decode, DecodeError, Encode};
 use ssz_derive::{Decode, Encode};
+use ssz_types::{
+    typenum::{self, Unsigned},
+    BitVector,
+};
 use std::hash::Hash;
 use std::{fmt, mem, sync::Arc};
 use superstruct::superstruct;
@@ -221,6 +225,8 @@ impl From<BeaconStateHash> for Hash256 {
 /// we add internal mutability to `milhouse::{List, Vector}`. See:
 ///
 /// https://github.com/sigp/milhouse/issues/43
+///
+/// This is overwritten with the Stable Container PoC.
 #[superstruct(
     variants(Base, Altair, Bellatrix, Capella, Deneb, Electra),
     variant_attributes(
@@ -312,29 +318,39 @@ impl From<BeaconStateHash> for Hash256 {
             )),
             num_fields(all()),
         )),
-        Electra(metastruct(
-            mappings(
-                map_beacon_state_electra_fields(),
-                map_beacon_state_electra_tree_list_fields(mutable, fallible, groups(tree_lists)),
-                map_beacon_state_electra_tree_list_fields_immutable(groups(tree_lists)),
+        Electra(
+            metastruct(
+                mappings(
+                    map_beacon_state_electra_fields(),
+                    map_beacon_state_electra_tree_list_fields(
+                        mutable,
+                        fallible,
+                        groups(tree_lists)
+                    ),
+                    map_beacon_state_electra_tree_list_fields_immutable(groups(tree_lists)),
+                ),
+                bimappings(bimap_beacon_state_electra_tree_list_fields(
+                    other_type = "BeaconStateElectra",
+                    self_mutable,
+                    fallible,
+                    groups(tree_lists)
+                )),
+                num_fields(all()),
             ),
-            bimappings(bimap_beacon_state_electra_tree_list_fields(
-                other_type = "BeaconStateElectra",
-                self_mutable,
-                fallible,
-                groups(tree_lists)
-            )),
-            num_fields(all()),
-        ))
+            tree_hash(struct_behaviour = "profile", max_fields = "typenum::U128")
+        ),
     ),
     cast_error(ty = "Error", expr = "Error::IncorrectStateVariant"),
     partial_getter_error(ty = "Error", expr = "Error::IncorrectStateVariant"),
     map_ref_mut_into(BeaconStateRef)
 )]
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, arbitrary::Arbitrary)]
+#[derive(
+    Debug, PartialEq, Clone, Serialize, Deserialize, Encode, TreeHash, arbitrary::Arbitrary,
+)]
 #[serde(untagged)]
 #[serde(bound = "E: EthSpec")]
 #[arbitrary(bound = "E: EthSpec")]
+#[tree_hash(enum_behaviour = "transparent_stable")]
 #[ssz(enum_behaviour = "transparent")]
 pub struct BeaconState<E>
 where
@@ -663,7 +679,8 @@ impl<E: EthSpec> BeaconState<E> {
 
     /// Returns the `tree_hash_root` of the state.
     pub fn canonical_root(&mut self) -> Result<Hash256, Error> {
-        self.update_tree_hash_cache()
+        Ok(Hash256::from_slice(&self.tree_hash_root()[..]))
+        //self.update_tree_hash_cache()
     }
 
     pub fn historical_batch(&mut self) -> Result<HistoricalBatch<E>, Error> {
diff --git a/consensus/types/src/execution_payload.rs b/consensus/types/src/execution_payload.rs
index 90940fbb9b9..665da1d6682 100644
--- a/consensus/types/src/execution_payload.rs
+++ b/consensus/types/src/execution_payload.rs
@@ -38,8 +38,12 @@ pub type ConsolidationRequests<E> =
         ),
         derivative(PartialEq, Hash(bound = "E: EthSpec")),
         serde(bound = "E: EthSpec", deny_unknown_fields),
-        arbitrary(bound = "E: EthSpec")
+        arbitrary(bound = "E: EthSpec"),
     ),
+    specific_variant_attributes(Electra(tree_hash(
+        struct_behaviour = "profile",
+        max_fields = "typenum::U64"
+    ))),
     cast_error(ty = "Error", expr = "BeaconStateError::IncorrectStateVariant"),
     partial_getter_error(ty = "Error", expr = "BeaconStateError::IncorrectStateVariant"),
     map_into(FullPayload, BlindedPayload),
@@ -52,7 +56,7 @@ pub type ConsolidationRequests<E> =
 #[serde(bound = "E: EthSpec", untagged)]
 #[arbitrary(bound = "E: EthSpec")]
 #[ssz(enum_behaviour = "transparent")]
-#[tree_hash(enum_behaviour = "transparent")]
+#[tree_hash(enum_behaviour = "transparent_stable")]
 pub struct ExecutionPayload<E: EthSpec> {
     #[superstruct(getter(copy))]
     pub parent_hash: ExecutionBlockHash,
diff --git a/consensus/types/src/execution_payload_header.rs b/consensus/types/src/execution_payload_header.rs
index 28bbfb9c048..aa594ac6f78 100644
--- a/consensus/types/src/execution_payload_header.rs
+++ b/consensus/types/src/execution_payload_header.rs
@@ -25,8 +25,12 @@ use tree_hash_derive::TreeHash;
         ),
         derivative(PartialEq, Hash(bound = "E: EthSpec")),
         serde(bound = "E: EthSpec", deny_unknown_fields),
-        arbitrary(bound = "E: EthSpec")
+        arbitrary(bound = "E: EthSpec"),
     ),
+    specific_variant_attributes(Electra(tree_hash(
+        struct_behaviour = "profile",
+        max_fields = "typenum::U64"
+    ))),
     ref_attributes(
         derive(PartialEq, TreeHash, Debug),
         tree_hash(enum_behaviour = "transparent")
@@ -41,7 +45,7 @@ use tree_hash_derive::TreeHash;
 #[derivative(PartialEq, Hash(bound = "E: EthSpec"))]
 #[serde(bound = "E: EthSpec", untagged)]
 #[arbitrary(bound = "E: EthSpec")]
-#[tree_hash(enum_behaviour = "transparent")]
+#[tree_hash(enum_behaviour = "transparent_stable")]
 #[ssz(enum_behaviour = "transparent")]
 pub struct ExecutionPayloadHeader<E: EthSpec> {
     #[superstruct(getter(copy))]