yes all two bolts big block have the small oil plugs on the side of the but the gm ho 4 bolts have big plugs on the side of them i think it 3/4 pipe and what gm cast in the block truck or hi pass. this differs on the block dose not mean much and the four bolt looks cool but you do not need it two bolts can take a lot i have been building big block for a long time and built some very hi hp on the stock two bolt block if you think you are building over 700 hp and running it at 6500 rpm and up for a long time like a boat or for the salt flats then i would use four bolt but gms stock block would not be my fist pick maybe a bow tie block . and if you build some thing like this there is better stuff to start with the fist thing i look at on any block is it been hurt dose it have sleeves in and dos it need more ? hase it been use up bored out to fare or line bored to much if so at that point i do not care if it two or four i will pass on it