My ford tauras has not been used in almost 3 yrs. not been started at all, just sitting in the drive way. Is the motor or tranny rusted shut now? Should I sell it for scrap or tow it to a shop to have it looked at?

When transmission sit for long periods ,the oil drains of the exposed gears and they rust.
they will probably turn ok but then noise sets in from the rusted parts , bearings will be part rusted, seals will be hard and will start to leak
cylinder walls will be rusted and rings may break on start up as they attempt to scrape the rust off
Consider this
The car is well past it's use by date
It will cost more than what it is worth to repair
The condition of the body ( rust etc) has to be considered
The choice is yours but personally I would junk it and if I needed another car , get something much younger where I could get parts

Tow it. cars have sat much longer and been brought back to life.