are our 6's drilled for 4 bolt mains....or do i have to stick to 2 bolt mains when i do my rebuild??? also if they are drilled for four bolt, what size and type will i need

sorry for reposting this but the last wouldnt lemme reply, so i figured it wouldnt let anybody....dang computers

 

All 2.8/3.1/3.4 motors are two bolt. Though GM sells 4 bolt caps it is intended for the aluminum Bowtie block. I thought about putting these on mine but the machinest didn't recommend it because it could "possibly" weaken the block walls. Of course, I wasn't going to take that risk so I decided instead to use ARP studs. If you want to strengthen the bottom end, this is the nest best alternative, IMO. The best of course is to by a bowtie block!