its a racing mini starter, it sits on the strait across bolt pattern so it needs to be properly shimmed. it is a late 70s block, but thats irrelevant, you could use this type of starter on a 1 peice rear late 90s block and need to use shims if you wanted, all the blocks are drilled for stagered or srait pattern.

i think im going to return the 153 tooth and order a 168 tooth and use my old stock starter motor that has never let me down. that racing starter scares me, it has way to much power and if its not perfect it chips teeth of... not wear them down, just blows them right off. i really didnt want to go back to the 168 tooth on a gear reduction stock starter because it will crank slow as hell compared to a non gear reduction starter on a 153 tooth, but you cant beat the reliability of a stock starter i guess.

thanks for all the replies, i posted this on a few other forums and got no replies.