howdy,
My '65 is shifting hard into drive and reverse. When I was installing a rebuilt carb a few years ago I accidently pulled on the vacuume line to the modulator and disconnected it at the modulator. It is shifting like that again and I replaced the short rubber piece that goes from the line into the modulator as it had a hole in it. That did not fix it and was wondering if the modulators go out?
Thx! Walt

 

don't forget you can also have a vacuuum leak on the other end of that like where it connects into the rear manifold. yes they go bad, and an adjustable unit is about $25 +/-