I would agree that the late 70's waggies have a better drivetrain for towing... 3.54 gears in Dana 44 front and rear. If you don't mind having a QT unit, the 73-79's with the TH400 will have a QT behind it. I have one and love it! they have a bad rep because of owners not using proper fluid or throwing lockout hubs on them. the later Wags have as low as a 2.73 and 3.31 gear.... 3.54's weren't an option in the 80's as far as I know. Chrysler took over the line in late 78-early 79 I beleive. From the early 80 and on, they were more into economy rather than HP and torque.
14" total lift