Is there a block difference between 1993 5.7L Chevy and 1996 Chevy?

Yes, there are block differences between a 1993 and a 1996 5.7L Chevy small-block engine. While both are technically "small-block" Chevy V8s, the 1996 engine is part of the generation commonly referred to as the "LS1" engine family (though the 5.7L in 1996 wasn't *technically* an LS1, it was a precursor), which has significant differences from the earlier generation 1993 engine.

The key differences related to the block itself include:

* Casting Number: The casting number on the block will be entirely different. This is the most definitive way to tell them apart.

* Materials & Design: The 1996 block likely features improved materials and casting processes resulting in a stronger and potentially lighter block than the 1993 version. This might include different wall thicknesses and internal passages.

* Bolt Patterns: While the general bolt pattern for accessories might be similar, there could be subtle differences that require attention when swapping components.

* Other Features: Things like the location of oil filter and other ancillary components could also vary.

In short, while both are small-block Chevys, treating them as interchangeable is risky. You cannot simply swap parts between them without verifying compatibility. You'll need to check the specific casting numbers of each engine to be certain of their differences and compatibility.