if i had things that far apart, id at least have the trans gone through. The torque converter in any stock auto regardless of the year is not well matched to the Cummins torque curve. Plus the stock trans in the motorhome is a non overdrive unit, which will, just like the pickups, will leave the cummins at a higher than happy rpm.
The ideal setup would be a pre 91.5 NON intrcooled engine, an A518 overdrive automatic with a good aftermarket torque converter and 4:10 or 3:55 rear end gears.
2001 QCLB SLT Laramie 4x4. Airdog 100, 1/2 inch lines, silencer ring MIA, Edge EZ, 3rd gen aluminum 17s, Posi-Lok cable 4x4, On board air.
other rides: 1966 Dodge Dart /6. 1969 Diamond Reo C101