I'm looking at buying a 91 Z28 parts car for the L98 in it. By the VIN number it is a L98 car. The guy who is selling it had bought it without a motor but bought a L98 out of a 1990 Firebird for it. Before I buy this car I want to make sure it really is an L98. Visually, the 305 and 350 are identical. Does anyone know what actually identifies the block as a 350 without tearing it down and measuring the bore or stroke? I know there are ID numbers stamped in behind the drivers side cylinder bank, but I can't seem to find a very credible source for what is what. Everyone seems to have a difference in opinion. If someone can get back to me asap that would be great, I'm going to look at this car again tomorrow.

 

Check the casting number on the block behind the driver side head.

 

I knew that part but I would like to know if anyone knows what numbers mean what pertaining to a 350 block compared to the numbers on a 305 block

 

Usually behind the left head will be a casting number and either 5.0 or 5.7 on most late model blocks. If the 6.0 or 5.7 are missing, look up the casting number on the web.