What year 360's have the "thicker bore"

You are gonna run into a whole lot of mishmash varied opinions on here. There is no real general consensus on what's the thickest. So I'd go out on a limb and say, the blocks are as varied as the opinions. You can end up with a buttload of core shift or they have a thin spot or you can hit a homerun and get a badass block. I would say the magnums have alot more solid metalurgy compared to a 70's block so I'd bank my money on one of those