1973 GMC Tranny Issues

[Ilyushin]

Hello this is my 1st post here, I have recently aquired a 1973 GMC 1/2 ton with a 350. It is a little beaten so to speak has 340,000 KM on it. The problem is, besides needing a tune up is the transmission (im guessing I do not know much about this sort of thing) it will start, and shift gears but when it's popped into gear sometimes it will move if you give it a fair amout of gas. I was thinking it was the tranny oil was low or something along those lines, but after we got it stuck in the muddy grass and tryed getting it out (tires are worn too lol) when we gave it more throttle all of a a sudden thick white smoke started pouring into the cab, from the hood and in between the cab and the box. We popped the hood and noticed where the dipstick for the tranny below it on the exhaust manifold the smoke was coming from there. looked like some oil had leaked onto the manifold and smoked, but after we tryed moving it again tranny oil started shooting outta the dipstick haha I have a few friends that can help but I just want to get some more opinions about it. I didn't pay anything for the truck so im not complaining, but wanna see what the issue is Thanks :canada

Update: Yesterday a friend and I went back to see it, tranny fluid is at a good level, engine oil is low, and looks as though the exhaust pipe is not connected with the manifold (sorry for my lack of proper terms :D ) and the white smoke seems to be coming from the exhaust. But there is residual tranny fluid on the manifold causing smoke from there too. I would not move yesterday, Im not too sure anymore lol thanks :)

[Mac_Muz]

Is the tranny oil pan about a square with one corner lopped off at about 45 degrees. If so that is a THM 350. I think but I am far from sure, that there is a vacuum pod on it, and on the outside, and that might be a part of the problem.

If so, there should not be tranny fluid inside the vac line heading to the intake manifold.

I am not sure what color smoke tranny fluid makes either.

I do know white smoke is made when coolant is burned, but maybe white smoke is made when ATF is burned.. So it seems you have a few choices.

The engine oil is checked with the engine OFF, but the tranny is checked warm at operating temp and with the engine running, incase you are not aware..

I am far from familar with the topic and so have no idea why ATF is forced out the filler tube.

My THM700 R-4 went kapustski recently and so I figured I could at least suffer in style repling to you... Mac