* Bellhousing: The critical factor is the bellhousing. You'll need a bellhousing designed to mate a small-block Chevy to a 2004R transmission. The engine block itself doesn't change significantly in terms of transmission bolt pattern over those years.
* Flexplate/Flywheel: You'll also need the correct flexplate (automatic transmission) for the specific engine and transmission combination. The 2004R uses a 153-tooth flexplate.
* Later SBCs (Post 1986): While the bolt pattern remains the same on the block, some later model SBCs (particularly those with later style serpentine belt systems) might require some adaptation with the accessories and exhaust manifolds to fit properly in the chassis.
In short, focus on finding the correct bellhousing. The year of the 350 engine is less important than having the correct mating parts.
