Differential blew up, just got new one

[CamaroAdam73]

Alright the 7.5" 10 bolt in my 88 Monte just went out, it's pretty gone. I wen't to pick up another differential that i was told was a 7.5 out of an early 80's monte, it's actually an 8.2 differential. Are the 8.2's better than the 7.5's ?

Second, this one's got what appears to be a 3.08 gear, my cam calls for a 3.73 or higher. I understand the car won't feel as responsive, but will it actually HARM the engine to turn a lower gear?

If i had to swap ring and pinion sets, what all would be involved? Also, if i do have to switch gear sets, should i go with a 4.10 VS a 3.73 set? I'll be driving the car daily.

 

[Kansas Bu Wagon]

Are sure sure it came out if a gbody? And are you sure it's an 8.2 and not an 8.5? I gbodys only came with 7.5 and 8.5 ten bolts... No 8.2's

 

[pontiacgp]

I have an 8.2 out of a 67 chevelle and it is better then the 7.5, it can handle up to 500 hp. There was an upgrade on them to change the pinion gears brass thrust washer to metal cause they would premature wear out. The 8.2 won't fit in the 7.5 housing and it needs 28 spline axles. Mine has the Eaton posi with 308 gears and that's a perfect ratio for my needs. I can still burn the tires off if someone wants to buy a new set... 🙂

 

[crotchss]

Kansas Bu Wagon is correct, they quit making 8.2 differentials in the early 70's. If you have an 8.2 with the right mounts put on it and the right width, yeah it would work and be stronger than the 7.5 rear. 8.5 would be the other rear dif that G-body's came with, which is a lot stronger. It came in the 80's 442's, Grand Nationals, and Hurst/Olds.

 

[pontiacgp]

In the A body the 8.2 came in two different widths, 64 to 67 it's 2.5 inches wider then the G body rears, the years 68 to 72 it's 4.5" wider than the G body rear.

did you look to see what blew in the rear end? There are parts available for the 7.5 so you may be able to fix it

 

[CamaroAdam73]

My 7.5 has over an 1" of pinion backlash and it started chewing the gears to bits, the pinion depth is way out now as well.

The only reason i think it's an 8.2, is because of the cover, looks just like an 8.2 cover with the diagonal indent in it. Strange thing is, it has the "ears" on the bottom of the housing like the 7.5 / 8.5 differential, but it doesn't have what the 8.5 / 7.5 should, it has the squared off corners with u shaped indents directly after going inward.

I'll have some pictures up later tonight when i crack this thing open, if it is an 8.2 then im screwed, or really lucky. The guy swears up and down it was pulled from a 85/86 Monte, we'll see.

 

[Kansas Bu Wagon]

7.5's have "fangs" while 8.5's have the 90 degree tabs (square corner tabs) in the bottom corners of the housing.

The 8.2 COULD have come out of a gbody monte if someone swapped it in. if it is in fact an 8.2, go and get the control arms form the guy you bought it from.

 

[pontiacgp]

maybe this will help to identify the rear end...here's a picture of my 8.2 in my GP..and if anyone notices the right rear spring has fallen from it's spot. The shocks are off and I run the short AK Bilsteins so the shocks keep the spring in place when the car is lifted

'

and here's a close up of the shape of the half circle cut out...

 

[Kansas Bu Wagon]

Here's the 8.5 in my shed... It came out of a hurst cutlass. The tabs are the best way to identify it.

 

[CamaroAdam73]

Thanks for the help guys, yeah turns out it was an 8.2 but it was from an early 70's Monte. GP, i got "half" of the control arms, and shocks, with the differential lol, they removed it from the car with a gas axe. Took the 8.2 back, no worries. I called a local salvage yard and they have a 7.5 from an 87 Monte SS for 250$ so i'm in luck.