most of the blocks i have came along with 010 is a 4 bolt main 350 running 370 hp. stock. if the rest of the #s are 3970010 then it is most likely a 350 4 bolt main running 370 hp. but gm did make a 2 bolt main that ran that much too. with the same #'s, i haven't yet came acrossed any to this day

Cd