Was doing some errands this morning and on the way home the transmission shifted a little strangely into 2nd. I had to let off the throttle for it to shift.

Fluid levels are correct and not burnt with no residue floating with a pinkish red color. Using Schaeffer's All-Trans Supreme.

I have read all of the threads related to the P0732 and the mechanical diode issue. Does the e99 4R100 have the mechanical diode? If not, what else could it be?

I also have the P0500 VSS sensor circuit fault which an old Ford mechanic stated could be related to a bad fuel sending unit which is definitely bad on this truck.

Am planning to go out and clean the sensor on the differential. Speedometer is working properly.

I have also noticed what appeared to be a small slip when in reverse a couple of times that I initially attributed to tire spin. Is any of this related?

Should I be prepared to rebuild/replace the transmission?