So there is a difference in a th350 from a chevy and th350 from a pontiac firebird with a olds 403. i always was under the impression gm is gm is gm. is it the shape of the bell housing or the bolt pattern and if so. Can i get a olds 403 engine to line up with a chevy th350( that was originally connect ed to a chevy350). Maybe by a adapter plate or something. i basically have a 78 camaro with a blown chev350 and a 79 formula firbird with a olds 403 that i want to mate togther to get a 78 camaro w/ an olds 403. Its all about budget .