I believe staggered bolts are for 168 teeth flywheel and straight pattern is for 153 teeth. (I hope)![S I had nothing but trouble with my SBC starters. Got to know the parts man on a first name basis, I saw him so much. Used to break starter noses, usually far away from home. I did the shimming and the clearance things, but they only worked for a while and then ----broken starter again!. Finally took it to a shop after it tore the teeth off the flywheel for the 2nd time. He drilled a 3rd hole in the starter and block between the 2 staggered bolts, tapped it, and it's been good for at least the last 4 years. I'm a happy camper now! No more noise from the grinding(That was always fun, only happened when someone was loooking at your car). If it's a mini starter like mine, I don't think anyone has a bracket to fit. That was always the problem, the starter would lift slightly and grind on the teeth. Tried the bracket when I had big Delco Remy's but they did the same thing.....CR