I have a 83 s10 with a 2.8 carbureted and 4 speed Borg Warner and its 4x4 and extended cab. So I recently had to pull the tranny in order to replace the throw out bearing. Cause I thought that might have been the source of the noise. Well the bearing was replacing did take some of the noise away. Now it makes noise in gears 1 2 and 3. And goes away in 4th. The repair Manuel said it took 3 pints of gear oil. I put 2 quarts. I've lost the owners Manuel. Any advice.
Make sure you use the right type and amount of oil. An under filled transmission makes more noise and can be more prone to grinding while you shift due to the gears being out of the oil if they are designed to use the drag from being in oil. 4th gear could be direct drive (1:1) and not actually be putting power through any gears, just power through a coupler on a shaft thereby making less noise than the other gears.