someone correct me if I am wrong, but, if the starter bolt patter are in a linear line paralell with the engine block end, the starter is for a 305 w/ the smaller flexplate. If the two starter bolts are off set, not in paralell with the engine block end, the starter is for a 350 or 400 with the 168 tooth flex. At least that is what i read years ago somewhere and it seems to work when i strip parts off at salvage yards--that info works for my truck in matching up parts. I know I have the off set two bolt hole starter and i have the 168 tooth flex.