727 Transmission Information
Bill Duster here's a picture showing how to tell a lockup transmission from a non lockup. The top picture is a lockup input shaft. The bottom is not a lockup. You can see how the lockup trans has the end of the input shaft turned down smooth. My guess is the 73 trans has the potential for being a stronger unit. It also may have 4 pinion planetaries where-as the 79 unit most likely has 3 pin planets.
Bill Duster here's a picture showing how to tell a lockup transmission from a non lockup. The top picture is a lockup input shaft. The bottom is not a lockup. You can see how the lockup trans has the end of the input shaft turned down smooth. My guess is the 73 trans has the potential for being a stronger unit. It also may have 4 pinion planetaries where-as the 79 unit most likely has 3 pin planets.