Starting in 1980 the Wagoneer / Grand Wagoneer had the differential moved to the passenger side of the vehicle. Starting in 1974 the Wagoneer / Grand Wagoneer wheel bolt pattern changed changed from 5 on 5 1/2 to 6 on 5 1/2. Most 1980 and newer Wagoneer / Grand Wagoneer had Dana 44 front axles, and the heavy duty corporate AMC 20 rear axle. In my humble opinion the Scout II rear axle makes a good choice for a rear axle upgrade for a Jeepster if you want a rear axle that is about 10" wider than stock. All Scout II Dana 44 have a wheel bolt pattern of 5 on 5 1/2.
The Grand Wagoneer / Wagoneer rear axles are a little wider than the Scout II axles.
The 1974 - 1976 Wagoneer front axle makes a good choice for a front axle upgrade if you want a front axle about 11" wider than stock. The 74 - 76 Wagoneer front axle has the correct spindle to convert to a Ford brake rotor / hub to do a very low dollar conversion to 5 on 5 1/2 wheel bolt pattern.
There are some 1974 - 1979 Cherokee wide track axles which are even wider than the Wagoneer / Grand Wagoneer axles!
Just be sure to measure the axles before you buy, it can be real expensive if you want modify Wagoneer / Grand Wagoneer / Cherokee axles to stock Jeepster axle widths.
dave