Welcome to Stovebolt Oskee!

Can we presume that it's still a closed drive line "torque tube" transmission? Do you have it pulled out, or are you looking for someone that will do that, the work on the transmission itself and reinstall?
These are known as SM318 3 speeds and if you've got some mechanical skills, are relatively easy to rebuild/refresh on your own. Lots of resources and previous discussions about that here, plus we can often help you find the parts needed for the work.
Let us know more please.
