Ditto on the sensitive throttle pressure adjustment. The problem existed when they were new, and 50 years of use and abuse at times hasn't helped the situation. One thing that exacerbates the problem is the fact that the HydraMatic has a fluid coupling, not a torque converter. The fluid coupling achieves an almost 100% RPM lockup, as opposed to the torque converter's 90% best effort. That 10% slip tends to soften the shifts on a torque converter equipped vehicle.
Keep tinkering with the throttle pressure adjustment until the shifting comes pretty close to what you want. It's going to be a fairly long process, and it's never going to be completely smooth or predictable. The truck transmissions also had slightly higher main line pressures and more positive shifts than the passenger car models. You really don't want a slippy shift with a lot of RPM flare-up between gears- - - - -that wears out clutches and bands in a hurry!
Jerry
