I have a '90 first gen automatic. Just got a fifth wheel camper for it (about 5,000 lbs I think) and the slightest hills require me to put the pedal to the floor and feel the truck struggle to keep 50 mph. Plus there is a little overheating (it is 100+ degrees here in the desert right now though) What can I do to make this engine do what it should. An overdrive switch installation? A transmission swap to a 5 speed manual? Putting the engine into a ford body? Getting a newer cummins?

 

Is this a stock truck or has it been modified in any way?

 

completely stock. there are new wheels on it however...ford wheels i believe.
New radiator as well. When I bought it the seller said it had been driven into a ditch and so work had to be done on the front. The original owner bought it new and used it to tow a fifth wheel on vacations, it's got 143k miles on it. The son of the original owner drove it into a ditch after his father passed away.

 

An increase in engine temp while towing is to be expected, as long as it doesn't hit the H mark you're fine. Sounds like the transmission has seen a lot of heavy use. An overhaul with a better torque converter will work wonders. A transmission with an overdrive will only be beneficial when not doing any heavy work as you will need to turn off the overdrive when towing anyway. Same thing with a 5 speed. Any conversion away from the 727 will have the benefit of increased fuel mileage, but would be a more costly repair unless you can find what you want at a less than the usual going price.

 

I called a shop in vegas, they can put a BD convertor in for less than $1500...I wasn't paying full attention to the prices, could have been around $1100. This seems reasonable to me.

 

get a pyro and trans temp gauge, fuel pin, spring, maybe a small set of injectors, bump the timing and crank the pump up. that will give you more than enough power to tow the fifth wheel comfortably. Then you just need to worry about your trans. either 5 speed swap it, or overhaul the auto with a nice TC. a 518 automatic swap personally i think would be beneficial as well. that overdrive is nice to have, even if you dont use it towing.

 

excellent information thank you!!