A 4028424 is a 76-77 trans. The guys are right about the bands. All rear bands are solid steel. Older front bands were solid but the newer ones were flex bands. Not sure when they started doing that but I think it was around 70. I'd bet the RV has 4 pinion planetaries front and back but you never know for sure until you take them apart. Yes using thinner clutch plates in the front carrier works so you can put more in it. Factory steels are all the same thickness but you can get aftermarket ones in different thicknesses. Just gotta have an assortment of selective snap washers to set the clearance right. Mopar made a spline angle change in 76 on the input shaft so make sure you use the correct front planetary gear set for a 76-90 trans. The older planetary from the RV may slip on but it'll strip out. If it a HD unit you want to use you'll have to find a pre 76 output shaft. The rear planetaries will exchange no problem.
