diff --git a/Cargo.lock b/Cargo.lock
index d362d6e..357073d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3456,7 +3456,7 @@ dependencies = [
  "libc",
  "option-ext",
  "redox_users 0.5.2",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3736,7 +3736,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -4726,7 +4726,7 @@ dependencies = [
  "js-sys",
  "log",
  "wasm-bindgen",
- "windows-core 0.62.2",
+ "windows-core 0.57.0",
 ]
 
 [[package]]
@@ -4944,9 +4944,7 @@ dependencies = [
 
 [[package]]
 name = "init4-bin-base"
-version = "0.18.0-rc.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "300b9df7fddc42d13d9d27d8a3def2c8982b1c02771523117984fe96be127843"
+version = "0.18.0-rc.8"
 dependencies = [
  "alloy",
  "async-trait",
@@ -5970,7 +5968,7 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -7070,7 +7068,7 @@ dependencies = [
  "once_cell",
  "socket2 0.6.2",
  "tracing",
- "windows-sys 0.60.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -10412,7 +10410,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.11.0",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -11529,7 +11527,7 @@ dependencies = [
  "getrandom 0.3.4",
  "once_cell",
  "rustix 1.1.3",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -12683,7 +12681,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index d471c90..21c22e1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,7 @@ name = "zenith-builder-example"
 path = "bin/builder.rs"
 
 [dependencies]
-init4-bin-base = { version = "0.18.0-rc.0", features = ["perms", "aws"] }
+init4-bin-base = { version = "0.18.0-rc.7", features = ["perms", "aws", "pylon"] }
 
 signet-constants = { version = "0.16.0-rc.8" }
 signet-sim = { version = "0.16.0-rc.8" }
@@ -63,7 +63,7 @@ alloy-hardforks = "0.4.0"
 alloy-chains = "0.2"
 
 # comment / uncomment for local dev
-# [patch.crates-io]
+[patch.crates-io]
 # signet-constants = { path = "../signet-sdk/crates/constants" }
 # signet-types = { path = "../signet-sdk/crates/types" }
 # signet-zenith = { path = "../signet-sdk/crates/zenith" }
@@ -73,4 +73,4 @@ alloy-chains = "0.2"
 # signet-journal = { path = "../signet-sdk/crates/journal" }
 # signet-tx-cache = { path = "../signet-sdk/crates/tx-cache" }
 # signet-bundle = { path = "../signet-sdk/crates/bundle" }
-# init4-bin-base = { path = "../bin-base" }
+init4-bin-base = { path = "../bin-base" }
diff --git a/src/config.rs b/src/config.rs
index 1296ccc..79c125a 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -12,7 +12,7 @@ use alloy::{
 };
 use eyre::Result;
 use init4_bin_base::{
-    perms::{Authenticator, OAuthConfig, SharedToken},
+    perms::{Authenticator, OAuthConfig, SharedToken, pylon},
     utils::{
         calc::SlotCalculator,
         from_env::FromEnv,
@@ -25,6 +25,9 @@ use signet_zenith::Zenith;
 use std::borrow::Cow;
 use tokio::join;
 
+/// Pylon client type for blob sidecar submission.
+pub type PylonClient = pylon::PylonClient;
+
 /// Type alias for the provider used to simulate against rollup state.
 pub type RuProvider = RootProvider<Ethereum>;
 
@@ -168,6 +171,10 @@ pub struct BuilderConfig {
 
     /// The signet system constants.
     pub constants: SignetSystemConstants,
+
+    /// URL for the Pylon blob server API.
+    #[from_env(var = "PYLON_URL", desc = "URL for the Pylon blob server API")]
+    pub pylon_url: url::Url,
 }
 
 impl BuilderConfig {
@@ -285,4 +292,9 @@ impl BuilderConfig {
         ((gas_limit as u128 * (self.max_host_gas_coefficient.unwrap_or(80) as u128)) / 100u128)
             as u64
     }
+
+    /// Connect to the Pylon blob server.
+    pub fn connect_pylon(&self) -> PylonClient {
+        PylonClient::new(self.pylon_url.clone(), self.oauth_token())
+    }
 }
diff --git a/src/tasks/block/sim.rs b/src/tasks/block/sim.rs
index 3963dc4..ea3cfe3 100644
--- a/src/tasks/block/sim.rs
+++ b/src/tasks/block/sim.rs
@@ -5,7 +5,7 @@ use crate::{
     config::{BuilderConfig, HostProvider, RuProvider},
     tasks::env::SimEnv,
 };
-use alloy::consensus::Header;
+use alloy::{consensus::Header, eips::Encodable2718, primitives::Bytes};
 use init4_bin_base::{
     deps::metrics::{counter, histogram},
     utils::calc::SlotCalculator,
@@ -62,6 +62,21 @@ impl SimResult {
     pub fn clone_span(&self) -> Span {
         self.sim_env.clone_span()
     }
+
+    /// Constructs the MEV bundle body from host transactions and the submission transaction.
+    ///
+    /// Combines all host transactions from the rollup block with the prepared rollup block
+    /// submission transaction, wrapping each as a non-revertible bundle item.
+    ///
+    /// The rollup block transaction is always included and placed last in the bundle.
+    pub fn build_bundle_body(&self, block_tx_bytes: Bytes) -> Vec<Bytes> {
+        self.block
+            .host_transactions()
+            .iter()
+            .map(|tx| tx.encoded_2718().into())
+            .chain(std::iter::once(block_tx_bytes))
+            .collect()
+    }
 }
 
 /// A task that builds blocks based on incoming [`SimEnv`]s and a simulation
diff --git a/src/tasks/submit/flashbots.rs b/src/tasks/submit/flashbots.rs
index 6b3d998..caee876 100644
--- a/src/tasks/submit/flashbots.rs
+++ b/src/tasks/submit/flashbots.rs
@@ -1,15 +1,12 @@
 //! Flashbots Task receives simulated blocks from an upstream channel and
 //! submits them to the Flashbots relay as bundles.
 use crate::{
-    config::{BuilderConfig, FlashbotsProvider, HostProvider, ZenithInstance},
+    config::{BuilderConfig, FlashbotsProvider, HostProvider, PylonClient, ZenithInstance},
     quincey::Quincey,
     tasks::{block::sim::SimResult, submit::SubmitPrep},
 };
 use alloy::{
-    consensus::TxEnvelope,
-    eips::Encodable2718,
-    primitives::{Bytes, TxHash},
-    providers::ext::MevApi,
+    consensus::TxEnvelope, eips::Encodable2718, primitives::TxHash, providers::ext::MevApi,
     rpc::types::mev::EthSendBundle,
 };
 use init4_bin_base::{deps::metrics::counter, utils::signer::LocalOrAws};
@@ -32,6 +29,8 @@ pub struct FlashbotsTask {
     signer: LocalOrAws,
     /// Channel for sending hashes of outbound transactions.
     outbound: mpsc::UnboundedSender<TxHash>,
+    /// Pylon client for blob sidecar submission.
+    pylon: PylonClient,
 }
 
 impl FlashbotsTask {
@@ -48,8 +47,9 @@ impl FlashbotsTask {
         )?;
 
         let zenith = config.connect_zenith(host_provider);
+        let pylon = config.connect_pylon();
 
-        Ok(Self { config, quincey, zenith, flashbots, signer: builder_key, outbound })
+        Ok(Self { config, quincey, zenith, flashbots, signer: builder_key, outbound, pylon })
     }
 
     /// Prepares a MEV bundle from a simulation result.
@@ -81,7 +81,7 @@ impl FlashbotsTask {
         let tx_bytes = block_tx.encoded_2718().into();
 
         // Build the bundle body with the block_tx bytes as the last transaction in the bundle.
-        let txs = self.build_bundle_body(sim_result, tx_bytes);
+        let txs = sim_result.build_bundle_body(tx_bytes);
 
         // Create the MEV bundle (valid only in the specific host block)
         Ok(EthSendBundle {
@@ -90,7 +90,6 @@ impl FlashbotsTask {
             ..Default::default()
         })
     }
-
     /// Prepares and signs the submission transaction for the rollup block.
     ///
     /// Creates a `SubmitPrep` instance to build the transaction, then fills
@@ -130,26 +129,6 @@ impl FlashbotsTask {
         }
     }
 
-    /// Constructs the MEV bundle body from host transactions and the submission transaction.
-    ///
-    /// Combines all host transactions from the rollup block with the prepared rollup block
-    /// submission transaction, wrapping each as a non-revertible bundle item.
-    ///
-    /// The rollup block transaction is placed last in the bundle.
-    fn build_bundle_body(
-        &self,
-        sim_result: &SimResult,
-        tx_bytes: alloy::primitives::Bytes,
-    ) -> Vec<Bytes> {
-        sim_result
-            .block
-            .host_transactions()
-            .iter()
-            .map(|tx| tx.encoded_2718().into())
-            .chain(std::iter::once(tx_bytes))
-            .collect()
-    }
-
     /// Main task loop that processes simulation results and submits bundles to Flashbots.
     ///
     /// Receives `SimResult`s from the inbound channel, prepares MEV bundles, and submits
@@ -176,7 +155,6 @@ impl FlashbotsTask {
 
             // Prepare a MEV bundle with the configured call type from the sim result
             let result = self.prepare(&sim_result).instrument(span.clone()).await;
-
             let bundle = match result {
                 Ok(bundle) => bundle,
                 Err(error) => {
@@ -186,6 +164,10 @@ impl FlashbotsTask {
                 }
             };
 
+            // Due to the way the bundle is built, the block transaction is the last transaction in the bundle, and will always exist.
+            // We'll use this to forward the tx to pylon, which will preload the sidecar.
+            let block_tx = bundle.txs.last().unwrap().clone();
+
             // Make a child span to cover submission, or use the current span
             // if debug is not enabled.
             let _guard = span.enter();
@@ -193,9 +175,10 @@ impl FlashbotsTask {
 
             // Send the bundle to Flashbots, instrumenting the send future so
             // all events inside the async send are attributed to the submit
-            // span.
+            // span. If Flashbots accepts, submit envelope to Pylon.
             let flashbots = self.flashbots().to_owned();
             let signer = self.signer.clone();
+            let pylon = self.pylon.clone();
 
             tokio::spawn(
                 async move {
@@ -209,6 +192,19 @@ impl FlashbotsTask {
                                 hash = resp.map(|r| r.bundle_hash.to_string()),
                                 "Submitted MEV bundle to Flashbots, received OK response"
                             );
+
+                            match pylon.post_sidecar(block_tx).await {
+                                Ok(()) => {
+                                    counter!("signet.builder.pylon.sidecars_submitted")
+                                        .increment(1);
+                                    debug!("posted sidecar to pylon");
+                                }
+                                Err(err) => {
+                                    counter!("signet.builder.pylon.submission_failures")
+                                        .increment(1);
+                                    error!(%err, "pylon submission failed");
+                                }
+                            }
                         }
                         Err(err) => {
                             counter!("signet.builder.flashbots.submission_failures").increment(1);
diff --git a/src/test_utils.rs b/src/test_utils.rs
index cb9d3e7..20119f4 100644
--- a/src/test_utils.rs
+++ b/src/test_utils.rs
@@ -56,6 +56,7 @@ pub fn setup_test_config() -> &'static BuilderConfig {
             block_query_cutoff_buffer: 3000,
             max_host_gas_coefficient: Some(80),
             constants: SignetSystemConstants::parmigiana(),
+            pylon_url: "http://localhost:8081".parse().unwrap(),
         }
     })
 }