I swapped in a take out 80e last year finishing by October IIRC, I didn't touch the tranny except for lushing the fluid out, making sure the pan was clean and dropping it in the truck. Its got an in line filter and 40k cooler with a thermal bypass and a +3qt pan. I did what I could to ensure long life in my low power but heavy application.

Fast forward to last week, 15 mile trip on the highway at the leisurely 65mph. No issue on the highway, converter's lock'ed in, no slipping noticed. At the top of the offramp the transmisison will not drop into 3rd, it goes to nuetral and the RPM's rise with pedal input, I get frusterated quickly as I need ot merge so I drop it manually into 3rd, that works. For the next 6 blocks to work I have no issue's with shifting. As I park in my space at work I have to back up but the truck doesn't want to go into reverse now, it takes a second and ater a tiny bit of pedal input and a split second of a bad grinding it goes. I park it for the rest of the day. After shutting it off I put my hand on the pan and it was hot, but not like boiling water so my guess is below 212*F at least by that time.

6pm rolls around and I get in to drive it home, 20 minute trip, no issue in 1st-4th. I never tried R again.

This weekend in response I drop the pan to find this:



All the peices are non-magnetic so Im assuming Al.

Anybody have a clue what occured or what is failing/has failed? I drove the truck a couple blocks after putting the pan back on and replacing the in trans screen and had no issue including reverse.

 

No educated guesses?