thanks for the info guys, mine is a 2 bolt with 2 freeze plugs. heres the bad part about mine. I just put eagle mains and align bore, moroso filler up to the freeze plug, clearance for 3.875, bored .040, decked .015. i have 7 350 blocks and my 383 thats on here for sale. i think ill build the 383 and sell the 400. again thanks guys you saved me a lot of money that was going in to it. Cj