This might be a retarded question, but what size is the bolt that threads into the crank snout?

I may have errr "misplaced" the original and could probably do with a new one anyway.

what size motor? they had 2 sizes for small block and 1 for big block.

it's a zz4 - so a late model small block. Sorry for not mentioning it earlier!

7/16" UNF or the metric eq. for a SB and 1/2" UNF for a BB and metric again IF they have went that way later!

pdq67

Mr gasket (at least i think its them) makes a bolt for this and it comes with the big washer. Its pretty cheap.