Ok, well, dropped the transmission pan today. And you were right, no drain plug.
I could have sworn that I had seen one on it before...
Anyway, pan was clean. There was a "doughnut" magnet about 2 1/2" across in the bottom of the pan. It had a layer of "sludge" on it, which felt smooth when rubbing it between your fingers. So at least not a bunch of bigger metal shavings or anything.
Removed the filter, it also looked ok... not that you can tell how dirty (or not) it is inside.
Valve body and everything else in the bottom of the transmission looked perfect and was clean.
Fluid wasn't bad, no burnt smell or anything. When you wiped it off on a white paper towel, it was a little brownish and darker, but was still red. Just not near as "pink" when compared to new fluid on a white paper towel.
While the pan was off, I did notice what I originally thought was a temp sensor or something that has been disconnected all this time, that inside the transmission there is a wire that goes over to what looks like an electromagnet, some type of solenoid.
Would this be the "downshift switch" you mentioned?? I had seen the blade connection on the outside of the transmission before, but there is no wire anywhere to connect to it. When I thought it was just a temp sensor, I wasn't too worried about it. But if this is the downshift switch, then I guess I'm going to have to figure out where its supposed to connect and run a whole new wire.
Anyway, Cleaned up the pan, and magnet, put the magnet back in the pan. Only had to clean off one or two small spots on the bottom of the transmission where the old gasket stuck.
The new gasket was of course folded up into a "ball" in the filter kit box, and didn't want to cooperate. So I used some of the "right stuff" gasket maker to lay a bead all the way around the pan, then used that to hold the gasket in place. Went ahead and put another bead of "right stuff" on top of the gasket while I was at it, just to make sure it got a good seal on the transmission.
Reinstalled the filter and pan. Then let it sit for about... half hour or so, just to give the "right stuff" some time to set up a bit.
Refilled the transmission with dexron VI back to the full mark. Took exactly 6 quarts.
Took it for a test drive, engine was still revving high before it would shift from 1st into 2nd.
So I took the transmission vacuum line a loose from the IP module, no change. Still revving high.
So, just as a test, I connected the vacuum pump line directly to the transmission hard vacuum line. At that point, the truck would shift from 1st to 3rd
(I think) at around 15mph. And it was so soft of a shift, you could barely even notice it. I think it was shifting directly into 3rd gear, because it only would shift once, so I think it was skipping 2nd gear at this point.
From this "test" I can only figure that it is the vacuum module on the IP that is bad.
So I'm going to search to find the part number for that, and try to get one ordered.
I
REALLY hope that this is my only problem, and that the transmission itself is fine. Certainly don't have the money right now for another transmission.
Especially right after replacing the heads and everything else...