My 1968 GTO has a 1972 WM code 455 cu.in block. All my research indicated this should have 4 bolt mains.and came from a 1972 Trans-Am. I am in the processreplacing the rear seal, and when I removed the pan was surprised to see 2 bolt mains any answers to this question would be appreciated. Dan

What is the actual casting code? That'll tell you for sure what's supposed to be under there.:cool:

http://www.pontiacpower.net/engcode01.html