I agree with Top Fuel in that the Transgo TFOD kit can be intimidating. I installed one in my 1992 a few months ago but I had the transmission out and upside down on the bench.
Having the transmission out helped a little in working on the servo, but the work on the valve body itself needs your full attention to detail. I worked on mine an hour or so, took a break and went back and finished it. If you pay close attention to the instructions it can be done.
I am very pleased with the results. The shifts are firmer, in fact, in my opinion, just right. I will be experimenting with line pressures soon and that will probably help even more. I have also noticed that I no longer have the convertor drain down when not running that I had before.
The addition of the TFOD kit along with the TCI torque convertor has made a large difference in my transmission. I am very pleased with it.
Overall, the old Torqueflite that our transmissions evolved from is really a pretty good transmission. The vast majority of the transmission problems I read about here on the TDR seem to involve the lock up convertor. It really makes me somewhat happy that my old truck does not have the lock up. I can get 22-23 mpg running 78 to 82 mph on the Interstate unloaded, and I don't think a lockup convertor would help that much.