I have a 1983 model diesel. It runs good, but when I am accelerating it up to highway speed, the second gear in the transmission is a problem. It doesn't shift out of second into third properly. It goes out of the second gear and into a "no man's land". Until I lift up on the gas (diesel) and let the transmission shift to third (or fourth) it will stay in the dead area. The car is a pleasure to drive except for that one point, and I do drive it quite a bit. I just try to remember that to shift into third, I need to remember to not force it. Any suggestions? One other point, I had the transmission fluid changed about 5000 miles ago. That did not change the problem.