Transmission

you said that the transmission is not shifting down,what gear? is the unit hard or gears clash while shifting? Is the unit lock in on gear? do the unit jump of the gear?
did you recheck the transmission fluid ?
can you or can't shift gear while the clutch is depress? or this happen while driving?
sorry to answer question by question, but I need more strong input so I won't tell you anything that is actually not the problem.
promess to answer you :)

thanks for responding the my answers to your questions are: it's not shifting past drive. Yes the unit is hard when changing.

It's automatic 700 transmission and while I was under the truck adjusting the linkage my wife was changing the gears. It would change into Reverse, Neutral and Drive but it wouldn't go further than that. I've checked the transmission fluid as well.

I had this transmission rebuild but I have no contact with that guy anymore, how can I tell if the transmission was really rebuild? Where do you suggest that I can get a book explaining this?

When I look at the transmission, everything looks new, new gaskets and new seals but I have no idea if what I'm looking actually is new. I had told the guy to installed heavy duty parts.

This truck has been a project for three years, on and off working on it....you know how that goes...problems arise and project needs to be on stand still now I'm back on it and basically everything is repaired and rebuild and I'm almost there only that I can't seem to get this last part together.

Why was the transmission rebuilt?
because of the same problems?