||Hi Joe, this is kind of funny, because I just bought the same coach 1 month ago from my fathers estate and drove it from arz. to ore. I was having the same problem. I would have to pull over-stop and start again. I was sweating bullets every time I saw a hill and had to down shift! As luck would have it a was talking to a truck driver at a fuel stop and he told me the secret. When down shifting you have to match the engine speed with the trans.speed. In other words double cluch-once into neutral and rev the motor-once more just before you stab it into third. The tranny did not come with syncro-mesh gears and it does take some practice. I hope this info helps and you get the hang of it. I'm still working on it!
Loren with a 1960 pd4104 coach.