I dont think 40k miles is awful, I usually shoot for 30k but I just havent had the time. I am going to assume with the TV clip gone pressure has been low and its been slipping, which is what caused all the trash.
I have been planning to tear it down and go through the truck to fix some things it needs. I needed to change the trans, diffs, and tcase oils - AC compressor, front main seal, front pinion seal, ect. The truck has 330k miles now and its been really good.
The trans was holding at WOT on the way home two nights ago, I dont see it dieing with new fluid, but I guess you never know.