I just picked up a rear. I"m trying to decode the letters and numbers on the pass side axle tube. Its 3TR G 084. I found that the 3TR is a 8.5 3.73 posi. My question is what is the G 084? Does the G mean chevy? Thats the only info I could dig up. I was told the rear came from a 87 Olds 442. Then there should be O not a G right? I'm confused

 

This is definitely an Oldsmobile sources 8.5" differential with 3.73 gears & posi. A great find. It is a bolt in for any 1978-1988 RWD GM A/G body of that era. Could definitely have come from an 87 442 but it may also have come from an earlier model year.


Note that these rear ends use C clip axle retention. Best to upgrade if you are planning to go fast. Otherwise good into the 11s.

 

Thanks Dave. Are there any other numbers on the rear that will tell me what it came from? Holy S#@t Dave 79 Oldsmobile cars since 1989!!

 

This rear is going into a 80 Cutlass. I've read that I need to cut my drive shaft 1 inch. Going from a 7.5 to a 8.5. I thought there was about 3in play in the driveline anyway. Am I wrong? Or is it that the 8.5 driveshaft is 4in shorter?

 

Anyone?