diff --git a/core/chains/evm/config/toml/defaults/L3X_Mainnet.toml b/core/chains/evm/config/toml/defaults/L3X_Mainnet.toml
new file mode 100644
index 00000000000..f593e39462d
--- /dev/null
+++ b/core/chains/evm/config/toml/defaults/L3X_Mainnet.toml
@@ -0,0 +1,23 @@
+ChainID = '12324'
+ChainType = 'arbitrum'
+FinalityTagEnabled = true
+FinalityDepth = 10
+LinkContractAddress = '0x79f531a3D07214304F259DC28c7191513223bcf3'
+# Produces blocks on-demand
+NoNewHeadsThreshold = '0'
+OCR.ContractConfirmations = 1
+LogPollInterval = '10s'
+
+[GasEstimator]
+Mode = 'Arbitrum'
+LimitMax = 1_000_000_000
+# Arbitrum-based chains uses the suggested gas price, so we don't want to place any limits on the minimum
+PriceMin = '0'
+PriceDefault = '0.1 gwei'
+PriceMax = '115792089237316195423570985008687907853269984665.640564039457584007913129639935 tether'
+FeeCapDefault = '1000 gwei'
+BumpThreshold = 5
+
+[GasEstimator.BlockHistory]
+# Force an error if someone set GAS_UPDATER_ENABLED=true by accident; we never want to run the block history estimator on arbitrum
+BlockHistorySize = 0
diff --git a/core/chains/evm/config/toml/defaults/L3X_Sepolia.toml b/core/chains/evm/config/toml/defaults/L3X_Sepolia.toml
new file mode 100644
index 00000000000..ee3e9df23ff
--- /dev/null
+++ b/core/chains/evm/config/toml/defaults/L3X_Sepolia.toml
@@ -0,0 +1,23 @@
+ChainID = '12325'
+ChainType = 'arbitrum'
+FinalityTagEnabled = true
+FinalityDepth = 10
+LinkContractAddress = '0xa71848C99155DA0b245981E5ebD1C94C4be51c43'
+# Produces blocks on-demand
+NoNewHeadsThreshold = '0'
+OCR.ContractConfirmations = 1
+LogPollInterval = '10s'
+
+[GasEstimator]
+Mode = 'Arbitrum'
+LimitMax = 1_000_000_000
+# Arbitrum-based chains uses the suggested gas price, so we don't want to place any limits on the minimum
+PriceMin = '0'
+PriceDefault = '0.1 gwei'
+PriceMax = '115792089237316195423570985008687907853269984665.640564039457584007913129639935 tether'
+FeeCapDefault = '1000 gwei'
+BumpThreshold = 5
+
+[GasEstimator.BlockHistory]
+# Force an error if someone set GAS_UPDATER_ENABLED=true by accident; we never want to run the block history estimator on arbitrum
+BlockHistorySize = 0
diff --git a/docs/CONFIG.md b/docs/CONFIG.md
index 4d8d6f6cf13..f36467c6d60 100644
--- a/docs/CONFIG.md
+++ b/docs/CONFIG.md
@@ -5400,6 +5400,194 @@ GasLimit = 5400000
 
 </p></details>
 
+<details><summary>L3X Mainnet (12324)</summary><p>
+
+```toml
+AutoCreateKey = true
+BlockBackfillDepth = 10
+BlockBackfillSkip = false
+ChainType = 'arbitrum'
+FinalityDepth = 10
+FinalityTagEnabled = true
+LinkContractAddress = '0x79f531a3D07214304F259DC28c7191513223bcf3'
+LogBackfillBatchSize = 1000
+LogPollInterval = '10s'
+LogKeepBlocksDepth = 100000
+LogPrunePageSize = 10000
+BackupLogPollerBlockDelay = 100
+MinIncomingConfirmations = 3
+MinContractPayment = '0.00001 link'
+NonceAutoSync = true
+NoNewHeadsThreshold = '0s'
+RPCDefaultBatchSize = 250
+RPCBlockQueryDelay = 1
+FinalizedBlockOffset = 0
+
+[Transactions]
+ForwardersEnabled = false
+MaxInFlight = 16
+MaxQueued = 250
+ReaperInterval = '1h0m0s'
+ReaperThreshold = '168h0m0s'
+ResendAfterThreshold = '1m0s'
+
+[Transactions.AutoPurge]
+Enabled = false
+
+[BalanceMonitor]
+Enabled = true
+
+[GasEstimator]
+Mode = 'Arbitrum'
+PriceDefault = '100 mwei'
+PriceMax = '115792089237316195423570985008687907853269984665.640564039457584007913129639935 tether'
+PriceMin = '0'
+LimitDefault = 8000000
+LimitMax = 1000000000
+LimitMultiplier = '1'
+LimitTransfer = 21000
+BumpMin = '5 gwei'
+BumpPercent = 20
+BumpThreshold = 5
+EIP1559DynamicFees = false
+FeeCapDefault = '1 micro'
+TipCapDefault = '1 wei'
+TipCapMin = '1 wei'
+
+[GasEstimator.BlockHistory]
+BatchSize = 25
+BlockHistorySize = 0
+CheckInclusionBlocks = 12
+CheckInclusionPercentile = 90
+TransactionPercentile = 60
+
+[HeadTracker]
+HistoryDepth = 100
+MaxBufferSize = 3
+SamplingInterval = '1s'
+MaxAllowedFinalityDepth = 10000
+FinalityTagBypass = true
+
+[NodePool]
+PollFailureThreshold = 5
+PollInterval = '10s'
+SelectionMode = 'HighestHead'
+SyncThreshold = 5
+LeaseDuration = '0s'
+NodeIsSyncingEnabled = false
+FinalizedBlockPollInterval = '5s'
+EnforceRepeatableRead = false
+DeathDeclarationDelay = '10s'
+
+[OCR]
+ContractConfirmations = 1
+ContractTransmitterTransmitTimeout = '10s'
+DatabaseTimeout = '10s'
+DeltaCOverride = '168h0m0s'
+DeltaCJitterOverride = '1h0m0s'
+ObservationGracePeriod = '1s'
+
+[OCR2]
+[OCR2.Automation]
+GasLimit = 5400000
+```
+
+</p></details>
+
+<details><summary>L3X Sepolia (12325)</summary><p>
+
+```toml
+AutoCreateKey = true
+BlockBackfillDepth = 10
+BlockBackfillSkip = false
+ChainType = 'arbitrum'
+FinalityDepth = 10
+FinalityTagEnabled = true
+LinkContractAddress = '0xa71848C99155DA0b245981E5ebD1C94C4be51c43'
+LogBackfillBatchSize = 1000
+LogPollInterval = '10s'
+LogKeepBlocksDepth = 100000
+LogPrunePageSize = 10000
+BackupLogPollerBlockDelay = 100
+MinIncomingConfirmations = 3
+MinContractPayment = '0.00001 link'
+NonceAutoSync = true
+NoNewHeadsThreshold = '0s'
+RPCDefaultBatchSize = 250
+RPCBlockQueryDelay = 1
+FinalizedBlockOffset = 0
+
+[Transactions]
+ForwardersEnabled = false
+MaxInFlight = 16
+MaxQueued = 250
+ReaperInterval = '1h0m0s'
+ReaperThreshold = '168h0m0s'
+ResendAfterThreshold = '1m0s'
+
+[Transactions.AutoPurge]
+Enabled = false
+
+[BalanceMonitor]
+Enabled = true
+
+[GasEstimator]
+Mode = 'Arbitrum'
+PriceDefault = '100 mwei'
+PriceMax = '115792089237316195423570985008687907853269984665.640564039457584007913129639935 tether'
+PriceMin = '0'
+LimitDefault = 8000000
+LimitMax = 1000000000
+LimitMultiplier = '1'
+LimitTransfer = 21000
+BumpMin = '5 gwei'
+BumpPercent = 20
+BumpThreshold = 5
+EIP1559DynamicFees = false
+FeeCapDefault = '1 micro'
+TipCapDefault = '1 wei'
+TipCapMin = '1 wei'
+
+[GasEstimator.BlockHistory]
+BatchSize = 25
+BlockHistorySize = 0
+CheckInclusionBlocks = 12
+CheckInclusionPercentile = 90
+TransactionPercentile = 60
+
+[HeadTracker]
+HistoryDepth = 100
+MaxBufferSize = 3
+SamplingInterval = '1s'
+MaxAllowedFinalityDepth = 10000
+FinalityTagBypass = true
+
+[NodePool]
+PollFailureThreshold = 5
+PollInterval = '10s'
+SelectionMode = 'HighestHead'
+SyncThreshold = 5
+LeaseDuration = '0s'
+NodeIsSyncingEnabled = false
+FinalizedBlockPollInterval = '5s'
+EnforceRepeatableRead = false
+DeathDeclarationDelay = '10s'
+
+[OCR]
+ContractConfirmations = 1
+ContractTransmitterTransmitTimeout = '10s'
+DatabaseTimeout = '10s'
+DeltaCOverride = '168h0m0s'
+DeltaCJitterOverride = '1h0m0s'
+ObservationGracePeriod = '1s'
+
+[OCR2]
+[OCR2.Automation]
+GasLimit = 5400000
+```
+
+</p></details>
+
 <details><summary>Mode Mainnet (34443)</summary><p>
 
 ```toml