I tried seaching, but came up empty. Here's my problem: http://shbox.com/1/rear_main.jpg I need a new rear main seal and housing for my LT1 but I don't know which I need because my block is not the original. It is a 4-bolt main GM crate LT1 that was installed in my car in 1999. I saw on shoebox's site where I could get the # off my block and figure out which one I need http://shbox.com/1/block_vin.jpg but those #s are not there on my block at all. Are they really that different? Can they be interchanged? If not, how can I figure out which one I need?

 

Any 1 piece RMS from a small block should work.

 

Thats what I thought too, but then I saw the difference in part #s from 1996 to 1997 and figured I better find out why the change and how important it is. Anyone know?