Rear end help

[Lue]

Hi Guy's..

I found a good deal on a 85 or 86 MC ss rear end (not shure what year he said). The guy said it's not a posi, but it has 3.42 gears. How would i be able to tell if it does have a 3.42. I know that the RPO code is GU6, but that's all i know..

 

[pokertramp]

Scratch that. I did a search in the box and GU6 is a 3.42 rear end.

 

[pokertramp]

BTW how good was the deal. Most of the ones I see are up to $400. a 7.5 posi I seen was $600.....

I can get a 7.5 non posi with 3.73 for about $400 but I am waiting for a 8.5 to pop up. 😀

 

[Lue]

Hows a $100 sound?

 

[NAILS]

in ny its pretty common size rear and easy to obtain ( 100-150 non posi in the junk yards )

i just sold a 7.5 posi 3.73 rear - drum to drum for $300. thats about the going rate here.

 

[Lue]

i just sold a 7.5 posi 3.73 rear - drum to drum for $300. thats about the going rate here.

Ok, so $100 bucks for one that's already bolted out of the car is not that bad then. All I would have to do is just pick it up, but i go back to how can i tell if it's a true 3.42? Is there a casting # or would i have to open it up?

 

[85 Cutlass Brougham]

There is a stamping on the passenger's side axle tube at the rear, but I forget the exact code you want to see. If you pull the cover, the number of ring gear teeth and pinion gear teeth are stamped on the ring gear. Do the math and you have it.

 

[Lue]

Thanx 85CB :wink:

 

[Blake442]

A quick way to check a gear ratio is to see how many turns of the pinion it takes to make the wheel turn one full rotation. So if it you spin the pinion about 3 and a half times, it's a 3.42. If you spin it say 2 and a half to 3 turns, then it's in the neighborhood of 2.73 or something crappy like that.

 

[87National]

All 83-84 Monte Carlo SS had a 3.42 rear, All 85-88 SS had a 3.73 rear. So if it is from an 85 or 86 and is the factory rear, it will be a 3.73. Either way, $100 is a good price.

Hi Guy's..

I found a good deal on a 85 or 86 MC ss rear end (not shure what year he said). The guy said it's not a posi, but it has 3.42 gears. How would i be able to tell if it does have a 3.42. I know that the RPO code is GU6, but that's all i know..