1960 rambler classic 196 smokes on start up

it's possible that at that age, there's a bit of oil seeping down the valve stems while it sits, which burns off when it starts. at 75,000 miles and however many years it's been, that would be completely normal. in a 20xx car that would be a problem, but in old design engines having a bit of oil in the guides is not a bad thing. if this is the case it's nothing needing fixing or attention.

My 1969 232 is having a similar issue, but it only blows a white-ish/grey cloud of smoke if I pump the accelerator once before starting to set the choke. It runs great otherwise, with no smoke whatsoever. It doesn't use any oil or antifreeze. If I don't pump the accelerator to set the choke before starting, it doesn't blow smoke. Is this something I need to be concerned about?

You said the vibration goes away when in neutral. Is that with the car still moving?

The most likely culprit is the flex plate between the engine and torque converter. The originals are a hardened steel and develop cracks over time. It's a simple steel plate -- you can have one mode at a local machine shop. Many double a plain steel.

The torque tube on the six cylinder car rarely dives any trouble. The u-joint may be worn (there is only one in front), and the center bearing could go bad, but neither of those usually give any trouble. They are sealed inside the tube away from dust and dirt. I've pulled u-joints with over 100K miles that were tight as new, and never had a center bearing go bad. But both could. The shaft should pull out with the bearing from the front of the tube once it is off the car.

Could be an internal transmission issue. Yours should have a vacuum modulator and an electric kickdown. If the vacuum line was off or the modulator diaphragm bad that could lead to hard shifting. The vac modulator reduces pressure at high vacuum (low engine speeds). if it's not working that will cause hard shifts between N/P and any moving gear as internal pressure would be higher than it should be.

Ok well I've decided to have the engine, trans, torque tube, and rear end rebuilt. Pretty much full mechanical restoration.

It has developed a crazy vibration between 1,2nd gear. It started with a squeak at low speed. Then a vibrating at high speed, around 70moh. It used to be super smooth. It's nearly undriveable now. Sad.

It's always shifted hard from N to D2 and R. Does anyone have an idea of what the vibration could be? It's really rough. And at the same time, all the vibration goes away when driving, when I put it in neutral.

I'd like to diagnose it before I pull everything out.

I can post a video.

That's it!! Knurling!! But on the inside it's tougher to do than on the outside...