REAR END SWAP - TIRED OF TRYING TO FIGURE IT OUT!

[ruffrider11]

So what I'm trying to figure out is what rear end I can put under my 81 Monte street stock circle track car. I need to get a 4.88 rear end gear and there's no such thing for a 7.5". Open spool is a rule, stock housing must be used. Max hp about 425. Thanks all.

 

[Ausby]

seems like the rules have you by the balls. if you can get away with saying a 8.5 is the stock housing you can use just about any gear you want. but a 4.56 is the lowest they make for a 7.5 and even then the pinion is so small they break alot.

 

[ruffrider11]

I should clarify - A stock housing must be used. What I'm hoping is that someone knows if there is an 8.5 rear end that can be bolted in - I'm aware of the posi 84 442 and 84-87 buick GN but as we all know they are hard to come by. Any other metric cars have an 8.5 that isn't a posi that would fit? I've been running the 4.56 for three years now and every year I worry about it exploding.

 

[BrownGP83]

Sorry man, but your SOL on the 8.5 in other G-bodys. GNs, 442s and H/Os were the only ones to get it. Even MCSS got the 7.5 and 7.625.

 

[megaladon6]

well you can always cheat. get an 8.5 out of almost any non-g-body car (they're a dime a dozen on camaros) and swap the mounts over. it's still a GM rear and the mounts are GM and in the stock position. it just takes good cutting/welding skills and a good jig.

 

[gpguy]

rear

if you can find a a body rear 65-72 posi it will bolt in to your g-body and you can put up to 456s in it the only thing you have to do is increase your wheel backspace to 5 and a half because it is 3 inches longer

 

[megaladon6]

but that would be a 12 bolt rear wouldn't it? that would be noticeably different and fail inspection.