All 302's would be the same, only the first 221 and early 260 I believe with two core plugs per side had different mounts. Small blocks after 1974 don't have the drilled and tapped hole at the rear of the block for mechanical clutch linkage. Late 81 (Maybe for 82 model year) 302's went to 50oz imbalance on rotating assembly as opposed to earlier 28oz imbalance.