So the 727 behind my 440 has always worked great, until now. 1st to 2nd shift is fine but It doesn't want to go into 3rd. It will rev and rev until I lift off the gas a little, then it will shift. It also wants to downshift from 3rd to second at light throttle pressure. Any ideas? Thanks.

There are a lot of places for fluid leakage in the 3rd gear hydraulic circuit. If it just changed all of a sudden, check the valve body. I lost 3rd gear in my car and found one of the passages in the valve body cracked. The front servo seals (and servo cover), stator to front drum seals, and the front drum piston seals are other places where fluid loss can occur.

3rd is also the first thing that goes when a tranny is wasted. Reverse is next. Probably time for a rebuild. Is your kickdown set correctly? Because if not, a 727 will not last long.

Same thing happened to us in our 340 car. If you are using a late 727 case, Chrysler didn't machine the groove in the front clutch drum (IIRC) correctly and the seal starts to leak where the up shift occurs later and later. An air test with the valve body removed will confirm this. If so, the trans has to come out. Replacing the seal will fix it for a while.

Sounds like worn governor sealing rings....they can be replaced without pulling the trans.

It's a late sixties case and the kickdown is and always has been adjusted correctly. I'm going to pull the pan and start looking for trouble tomorrow. I'll keep you posted.

Your trouble isn't inside the pan; lift-throttled shifts to 3rd and uncommanded downshifts to 2nd are classic governor sealing problems.