Mopar's small block V8 — the LA-series — is a long-running engine family that spans from the 1960s through the 1990s. The 273, 318, 340, and 360 all belong to this family and share the same bellhousing bolt pattern.
WHERE TO FIND THE CASTING NUMBER: The block casting number on a small block Mopar (LA-series) is located on the left side of the block (driver's side). It is cast into the block and should be visible after cleaning.
COMMON LA-SERIES CASTING NUMBERS: 2780930: 273 or 318 ci — used throughout the 1960s in A-body and B-body Mopars; also found in trucks 3418793: 360 ci — used in 1971 and later applications; common in trucks, vans, and police-spec vehicles through the 1980s and into the 1990s 2951745: 340 ci — used in high-performance applications 1968–1973 (Dart, Duster, Barracuda, Challenger)
BELLHOUSING COMPATIBILITY: All LA-series engines — 273, 318, 340, and 360 — share the same bellhousing bolt pattern. This means they are largely interchangeable in terms of mounting and transmission selection. A 318 and a 360 will fit the same motor mounts and bellhousing.
CYLINDER HEAD COMPATIBILITY NOTE: While the blocks are interchangeable in terms of mounting: • 273 and 318 heads have smaller ports and different valve sizes • 340 and 360 heads have larger ports and larger valves • 340/360 heads will physically bolt to a 273/318 block, but porting and combustion chamber dimensions differ • Do not assume that any LA head will match any LA block for performance purposes — confirm specs for your application
For help confirming your engine or finding a replacement, contact us at 1-844-XPARTS-1 or support@expediaparts.com.
