9 bolt, 12 bolt, what's the difference?
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
While that was a helpful answer, i'll elaborate...
That's the # of bolt holes on the back of the "pumpkin" or differential housing. It's the EASIEST way to tell which it is.
10 bolts are basically the norm for our cars. Weak. 9 bolts are stronger, much more rare, and therefore hard to find parts for.
12 bolts are basically the strongest factory axle GM made, bigger overall, so you can beef it up to be almost invincible
That's the # of bolt holes on the back of the "pumpkin" or differential housing. It's the EASIEST way to tell which it is.
10 bolts are basically the norm for our cars. Weak. 9 bolts are stronger, much more rare, and therefore hard to find parts for.
12 bolts are basically the strongest factory axle GM made, bigger overall, so you can beef it up to be almost invincible
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Posts: 17,264
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From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Originally posted by Sonix
12 bolts are basically the strongest factory axle GM made, bigger overall, so you can beef it up to be almost invincible
12 bolts are basically the strongest factory axle GM made, bigger overall, so you can beef it up to be almost invincible
GM offered 3 different 10 bolts. The newest is also the weakest at only 7.5/7.625. They were also offered in 8.2" and the more popular 8.5". Nothing is interchangeable between these diffs.
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