Do not let it intiminate you if you are going to do it. Usually pretty simple with the older boxes. Last one I did was a five ton truck and the transmission was a little heavier. Replaced syncro ring and second gear. Was very quick. For expediency if you can locate another transmission it might be the way to go. Time waiting for parts when you establish what you need might take a few days. Think there is even a description in the haynes manual of the teardown and rebuild process. Usually not required as it is so straightforward. If you just require a new bearing or bearings they might be obtainable from a local bearing house if you have one in your area. That way you could have it out, bearing or bearings replaced, and back in the same day. My main point is it is generally a pretty easy thing to do if you decide to tackle it. Where you running with low transmission fluid? These boxes are supposedly pretty rugged but everything fails eventually.