Pulled the drain plug, and nothing but water came out. Not rusty water, but mostly clear. I went back up top, and the shifter now is not stuck, in fact, it shifts rather smoothly now.
I'm puzzled to say the least. But happy!

I also pulled the plug from the T.C. because IIRC, they share the same fluids. Nothing but a few drips of sludge came out. It shifts also ok. So, I think I will flush them both out with ATF and diesel, and refill with gear oil.
It is good enough for me right now until I get the engine running to see if it is worth saving.
On another note, with the tranny un-stuck, the engine spins over a whole lot easier. By hand I'm talking. It feels normal now. I believe I will pull the tub and swap frames for the unmolested one on my parts heep.