Those transmissions are usually as tough as a two dollar steak. Just pour a couple of quarts of kerosene or Diesel fuel in, and spin the gears. If it's out of the vehicle, find a drill motor big enough to clamp onto the pilot bearing area of the input shaft, and spin away! You're not going to harm it at all by circulating a solvent in it, and whatever doesn't drain out will evaporate pretty quickly. In the vehicle, I just drain the old lube, fill with solvent, and run the engine with the tranny in neutral for a few minutes.
Jerry
