I just bought a 91 rs with the 305 and automatic. The car came with a borg warner 9 bolt that I can swap into the car but the thing I dont like about it is that it only has 2.77 gears. The stock rear howles a little. Would you guys swap for the 9 bolt and 2.77 or sell it.

 

most likely your current 10 bolt has a 2.73 anyway. Does the BW have the same brake setup?

 

The bw has disk brakes. I would like to have 3.42 or 3.73 or something around that.

 

There are more aftermarket options for the 10 bolt. If your current rear is drum and the BW is disc then you'll have to do some work to convert the brakes. If you want to go up to a 3.42 or 3.73 (3.45 & 3.77 in the BW, i think), then either way you'll need to rebuild the rear.

I would sell the BW and use the money towards rebuilding the 10 bolt.