reaer end identification help
#1
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Car: '91 firebird
Engine: 350 4bbl
Transmission: t56 6 speed manual
Axle/Gears: limited slip, 3.73 gears
reaer end identification help
i wanna find out what kind and size reaer end i have in my 91 firebird. it has a 305 and had an auto. there was a number on the bottom of it its 22522676. i really want to find out what the size is, i cant seem to find it from any research. from wht i can find its probably a gm 10 bolt open with 2.73s, though am not certain, but what i want to know is the size 8in, 7.5in, 8.5in ... ? any help would be appreciated
#2
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Car: GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: Aussie 9-bolt/3.27 posi
Re: reaer end identification help
Count the rear end cover bolts.
9 bolt heads = A 9-bolt.
10 bolt heads = A 10-bolt.
Stock is the 7.5". You can jack the rear of the car off the car (use jack stands not just the jack), put the tranny in Neutral, then rotate the tire 1 full revolution & count the # of turns the driveshaft makes. 3 tire rotations to 1 driveshaft rotation is equal to a 3.08 gear. 2 3/4 tire rotations is equal to a 2.73 gear.
Those are your 2 most likely gears, for your combination.
As for Open vs Posi....If Open, only the Passenger side will turn or if both turn, the Drivers side can be very easily stopped & the tires will rotate in opposite direction. A Posi will make them rotate in the same direction.
9 bolt heads = A 9-bolt.
10 bolt heads = A 10-bolt.
Stock is the 7.5". You can jack the rear of the car off the car (use jack stands not just the jack), put the tranny in Neutral, then rotate the tire 1 full revolution & count the # of turns the driveshaft makes. 3 tire rotations to 1 driveshaft rotation is equal to a 3.08 gear. 2 3/4 tire rotations is equal to a 2.73 gear.
Those are your 2 most likely gears, for your combination.
As for Open vs Posi....If Open, only the Passenger side will turn or if both turn, the Drivers side can be very easily stopped & the tires will rotate in opposite direction. A Posi will make them rotate in the same direction.
#3
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Re: reaer end identification help
If the rear is OE, it's a 10-Bolt, so here's the FAQ:
https://www.thirdgen.org/forums/tran...-10-bolts.html
JamesC
https://www.thirdgen.org/forums/tran...-10-bolts.html
JamesC
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Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: reaer end identification help
According to the TGO tech data, the only option for a 91 Firebird with a 305 and an auto is the 2.73 gears. Your diff will be a 7.5/7.625" ring gear size and it will use 28 spline axles.
That's all assuming it's still original.
That's all assuming it's still original.
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