I've had 6 T-Bird's that have been daily drivers, so it's been a fleet issue with me. I've re-used motors off parts cars as much as I can, but and tried some window "goop" first...which was years ago. It's that tarry junk that is usually used on windshields, I think. It held up great until hot weather.
Since that mess, I wanted what was known to work, so I bought a applicator cartridge of the adhesive. It lasted 7-8yrs at least...seems like I might have finally tossed it last time I had to use it. If RTV works, that's great too though! Less chemicals to keep on hand!
There are multiple weak links that develop - several with the motor (shaft, large plastic gear, the stubs), the window clip adhesive are the common ones. I've worn out the channels too (wore the fuzzies off)...which causes problems too, as you can imagine. I wore out a regulator too....that was fun replacing. With the other items making it harder to get the windows up and down, you definitely want whatever works for a long time....do you know the condition of your window channels? Or whether there is any struggle to rolling your windows up or down? If there is, I'd say RTV may be the way to go, if you're like me and don't start tearing into something immediately after a nuisance problems shows up.