The old alternator in the TBird appears to not working. Will be going down to the parts house and having it tested. Question. What size alternator should I replace it with, 40A or 55A.. A/C, power windows.

If you want to keep the original look, the 55 amp unit is the correct one. If you want more capacity, a 3G alternator out of a Taurus or Mustang will give you about 130 amps.

Can your local auto electric shop rebuild and up the amps in your original one? I remember reading that somewhere.