1984 K10 4wd trans issue?

[la67dartgt]

Hi Everyone,

 

Truck is an 84 shortbed K10 with 350/700R4, entirely stock except for the wheels and tires.

 

About two months back, and for reasons related to my stupidity, I accidently ran the trans low on fluid. I learned of this while in O/D on the highway at 60 mph, when I suddenly realized the TC was no longer able to keep a lock. The engine started going up and down, the TQ unlocking and locking. I saw what appeared to be white smoke coming out behind the truck. Pulled it off the highway, checked the fluid and there was no fluid registering on the dipstick. Filled it back up and away I went.

 

I was quite scared that I had destroyed it, but to my surprise discovered that the truck drove fine. TQ locked up as it always did, trans shifts as it always does, firm and smooth, etc. I have even towed the 6x12 enclosed uhaul trailer a couple of times since then.

 

What I've only recently realized is that when I'm going uphill, particularly long stretches of uphill, the truck struggles big time. It's as if the motor is completely gutless, and cannot get the truck up the hill. The trans kicks down to keep the engine in the power band, and the engine runs like a champ, but the truck just slows and slows until the top of the hill. I also see the white smoke that I saw during the earlier empty fluid issue if the hill is long enough, and then a burning smell. After I crest the hill, all is good. Shifts normal, lock up is normal, down hill and on flat stretches everything is fine. Engine is plenty strong from a stop and up to highway speeds. The smoke makes me think of the trans when i had the fluid issue, but I've never heard of a trans seem to "slip" while not slipping. Does that even make sense? While the truck has never been a power house, it has always gotten itself up a hill.

 

Has anyone seen this before? Is the TQ bad? Or the whole thing? Or am I barking up the wrong tree? I have not yet changed the fluid and filter, so I don't know what's in the bottom of the pan. That's on my list for today or tomorrow.

 

Thank you,

Don