late model 350 blocks 2 or 4 bolt mains?

[bradh]

Hi, new to the forum. I just bought a decent 72 C10 with 150k in unmolested condition. It runs and drives great but it leaks oil, leaks tranny fluid and burns oil so I was going to go ahead and build a 350/th350 to swap into it later. I also have a factory LT4 roller cam I took out of my car so I would probably be able to use that in the late model roller 350 as long as I use the correct timing chain (I think, I'll have to dig some more to find out). My question is do late model 350s all have 2 bolt mains or do some have 4 bolt and if so which ones? Thanks.