i agree, low tranny fluid will usually cause slippage. from what you describe it actually sounds like it is working more like it is supposed to haha.
i have a good idea what happened. besides fluid level the one thing that has a drastic effect on how the tranny shifts is the line pressure cable. its the one on top of the motor w/ orange boot next to the throttle linkage. id bet when they put the motor in they adjusted it to where it should be when it was installed on the bracket. was probably adjusted on the low side when you had it before. if you wanted to check it- with the car off manually move the throttle cable to wot. there is a little crimp on the line pressure cable that should come to the edge or past the orange boot. id bet its closer to being correct now than it was before which is why you experience firmer shifts.
congratulations! i think you have nothing to worry about
i have a good idea what happened. besides fluid level the one thing that has a drastic effect on how the tranny shifts is the line pressure cable. its the one on top of the motor w/ orange boot next to the throttle linkage. id bet when they put the motor in they adjusted it to where it should be when it was installed on the bracket. was probably adjusted on the low side when you had it before. if you wanted to check it- with the car off manually move the throttle cable to wot. there is a little crimp on the line pressure cable that should come to the edge or past the orange boot. id bet its closer to being correct now than it was before which is why you experience firmer shifts.
congratulations! i think you have nothing to worry about
