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Discussion Starter #1
Is a 8.5 10 bolt with 2.56 gears rebuildable to a 3.73 gear ratio with a posi? And is it strong enough to handle a 400 - 500 horse power street engine?
 

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it is if you spend the money,

i dont see why it wouldnt hold up, unless you somehow very badly shocked it, in which is how ot break a gear or spiders or a shaft

but rarely happens with the 8.5


good luck
 

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10 bolt

tinman386 said:
Is a 8.5 10 bolt with 2.56 gears rebuildable to a 3.73 gear ratio with a posi? And is it strong enough to handle a 400 - 500 horse power street engine?
I ran one in a 79 trans am with 450 hp+ and a 2:73 rear gear, 700r4 trans and 295-15 tires--rear held up fine but not the trans., but to go to a 3:73 you must change the posi carrier.
 

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This may sound stupid but im not familiar with rear ends. What is the posi carrier? And if i have a open rear end it doesnt have posi so do i still need to change this? Basically if i buy this rear end i want to be sure that i can take it to my local tranny shop and have it built to the specs i want.
Thanks for your help guys
 

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okay tinman, I'll try to bring you up to speed...

posi is what GM called their limited slip rear ends. pontiac called theirs safe-t-trak, ford equa-lock or trac-lok, mopar sure grip, american motors twin grip, and so on, but they're all limited slip type rear ends. lift both rear tires off the ground and turn one by hand; if both tires turn the same way, you probably have a limited slip. if the other tire turns the opposite way, you probably have an open rear. but the only way to know for sure is to take the cover off and look. but if you have 2.56 gears and are going to 3.73 gears, just like that good looking harv said, you must change carriers, so what you have in there now won't matter (you can use an adapter ring but it's not recommended on a limited slip or any performance application).

so, to answer your questions, yes if you buy that rearend you can put any ratio/posi unit in it that you like. and yes, with richmond gears and an auburn or eaton carrier, you can run 500hp through that rearend without even beginning to strain it.

I just finished my 8.5" 10 bolt today. it was a 2.56 open; now its a 4.10 auburn, so there you go ;) btw, make sure your 8.5" 10 bolt is an 8.5" 10 bolt. I thought thats what I had but it turned out to be a 8.8" 12 bolt mp, which looks almost identical on the outside but its junk junk junk.
 
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