Diesel Bombers - 47RE Problem!!! Cant drive!

Last night I was towing a trailer that was about 8000lbs and my truck was running perfect without a problem including the transmission. I stopped to take a pee then got back on the freeway and about 30 seconds after that I was on a slight downhill and push on the throttle and had nothing. I pulled over and turned the truck off and let its sit then checked all my fluids and electrical connections. It droved about 30 feet then it did it again like i was in neutral. I ended up getting it towed.

Everytime I start up the truck and go to drive it makes it about 30 feet then like "slips out of gear". I have no clue what the problem is. I was hoping someone else does.

Also I hooked up a code reader and it only throws the two codes that come from the torque converter lock up switch. No shift solenoid or sensor codes.