Putting a motor like that in isn't as bad as you might think on the frame and such. It's not going to be loaded very much. A 5.9 Cummins in a medium duty truck spends its life at full power so it needs a huge cooling system and 500# transmission and telephone pole driveshaft because those are going to be loaded all the time. It's actually hard to warm up an empty medium duty truck because of the size of the cooling system--which is meant to deal with a 200hp constant load. In a Ranger it's going to be hard to actually load the chassis up--it's just going to spin the tires. He's not going to need the cooling system a 3500 Ram is going to need because he is going to only use short bursts of power--not even near his maximum power because it won't stick to the ground.
There is a magazine article circulating that has an F150 with a 15-liter Cummins in the bed mounted to a NV4500 tranny--a 2,000ft# motor hooked to a 500ft (light duty rated) tranny. It's fine because there's no load there to actually transmit.
There is a magazine article circulating that has an F150 with a 15-liter Cummins in the bed mounted to a NV4500 tranny--a 2,000ft# motor hooked to a 500ft (light duty rated) tranny. It's fine because there's no load there to actually transmit.