Truck Repair: Cummins engine replacement feasibility, cummins engine, jeep cherokee

Question
Cliff
I have a 6BT5.9 160 hp engine with an Allison AT542 transmission. This is mounted in a 1990 Oshkosh chassis carrying a 31 foot class A motorhome.

Engine has 143,000 miles on it, injectors have original paint that has not been touched by a wrench.

Engine runs reliably, tranny too. Motorhome weighs about 15,000 to 16,000 lbs loaded. Pulling a 3000 lb Jeep Cherokee is fine if a bit slow on the flat. Usually drive the jeep seperately over mountain passes. Tranny does not lock up so top speed is 60 mph and little or no compression braking until I get into 2nd gear.

I have looked into upgrades on this engine and transmission, $7-10K for engine and $7K for a locking tranny (632?)...

What is the feasibility of installing a 5.9 cummins from a wrecked Dodge pickup with the Dodge/Allison tranny? Economics? Fit? Cooling? New  Exhaust etc?

Am I just having a dream or should I persue this further?

Thanks for your opinion.

   Hugh

Answer
They are the same engine basically.The problem would be the year model of both engines.The newer engines have a charge air cooler in front of the radiator(91 & newer).The engine blocks are the same.I assume that yours being a 160 HP it is a pre 1994 engine.It will take so looking into,but you might can up the HP with just injector & pump change depending on the CPL.I think the rotory pumps only went to 190 HP.The DODGE transmission will not work because it is a DODGE transmission.The exhaust manifolds are different,It will fit in like the old engine.Pan will be different,DODGE capacity is smaller.