A friend of mine has a 87 Cutlass with a 2.55ish gear in it. We would like to change it to a 3.73. Can you do this on a 2 series carrier? Do I need a spacer? Or is there a thicker gear made for a 2 series gear swap? Or do I need a 3 series carrier? I dont know if it a 7.5 or a 8.5 rearend. Could you tell me how to tell if it is a 7.5 or 8.5? Also the stamping on the pass side axel tube has 2B A C273 2 stamped on it. A book I have says the third ID will tell me what it came off of C=Chevy O=Olds B=Buick p=Pontiac. As you can see its A. What is this? Iam thinking a miss print or swapped from something else. Any help would be great,Thanks Dave
Dave-here's part answer=I believe in '87 that both the Olds 442 and Monty SS had the 3.73 in the 7.5 rear. The 8.5 in 3.42 came with the Buick turbo cars. Either should be a bolt in-good luck
You will need a type 3 carrier to use 3.73 gears in that housing it is probaly a7.5 and should be realtly easy to find a carrier Ken K
Aftermarket 7.5 gears are avail in thick version, so one can use the more common high ratio posi carrier (2.29-3.08). Richmond is one company that makes these thick 7.5 gears, usually $20-25 more than normal low ratio 3.73 7.5 gears. :3gears: Roger
Thanks for the input guys. Roger that was my thought. I saw a parts catalog that had a few different gears listed but did not give up much info on which to use and when.
8.5 3.73 ? 84-88 olds 442's had an open 8.5 with 3.73's where monte ss had 3.73 gears(not all were posi's) but in a 7.5. gn and turbos had 3.42 geared 8.5's(posi)