Weird Transmission Problem 99 T&C

I have just had the transmission rebuilt in my 1999 town and country, literally yesterday. It drives ok, but the RPMs never seem to fall back. In other words, it never seems to change gears. The RPM gauge steadily climbs, until about 5500 rpms, which is a shade under 70mph. This seems to be the maximum speed I can get to, and the engine is very loud. I have no idea what has made this happen, but I am hoping someone out there can shed some light on this over the weekend before I go to my mechanic with this. Any help would be greatly appreciated.

If you keep running at 70 mph in low gear you'll be stuck on the side of the road waiting for a tow. Check the fluid level when the tranny is warmed up. Make sure all the electrical connectors on the front of the transmission are connected. Beyond that take it back to whoever rebuilt the transmission pronto. There are far too many causes for this for you to worry about. Keep it below 40 mph.

It's not shifting, get it back to the shop immediately.

It's not shifting, get it back to the shop immediately.