DON - I agree, looks like a well kept truck for that age & miles.
Tom is correct, keep that truck in the shop during winter and drive your 4X4. Dad had a co-worker who drove a K3500 4X4 dually to work years ago driving 18-wheel fuel transports. He was driving to/from work one day in a snow about like that shown in your first group of pic's. The outside rear tire caught the snow along the track in the road and spun him around, then off the road. It was the END of his truck driving career even though he lived.
It'll be nice when the Big Three, FORD, Chevy, & Dodge catch up to the Big Truck technology of air ride suspension. Last company I worked for replaced a POS FL70 Freight-shaker with an IH 4300 with air ride rear suspension & seat at my suggestion. We had both trucks four years, same driver all the time, and the IH got better MPG, was MUCH nicer to drive, just got normal maintenance for over 200,000 miles. No repairs, leaks, or problems with the IH. The Freight-Shaker leaked constantly, vibrated so bad the driver had to steady the mirror to back into the dock, and the only time we had it loaded close to it's rated capacity it broke all the leaves in one rear spring and dropped the box onto the rear tire a block from our plant. Normally we hauled 2000 to 6000 pounds in a truck rated to 25,999# gross. The Freight-Shaker was hauling about 8000-9000 pounds when it broke the springs, so it weighed about 23,000#. It was a constant PITA for the 175,000 miles we had it. There's a reason IH OWNS the medium duty market on trucks.
Not sure what manual 5-spd Dodge used in that vintage truck but I'd check it out. The Cummins was pretty weak stock from the factory back in those days and the tranny may not like double the factory HP & Torque. ALSO, How much fuel can you carry on-board? For trips towing your 5-er You may want to add a aux. tank in the box. You can NEVER have too much fuel! Although I did almost once, I goofed a little on loading my load coming home from Chicago, was a tad heavy on the drive axles of my semi-truck, 31,900# on a 32,000# maximum, and my fuel tank was almost bone dry, I was going to stop at the truck stop just a half mile past the weight station. The fuel tank was maybe a foot from the front drive tire so most of the weight of the 50 gal of fuel I was going to get was on the drive axles, so I was about 200-250# over on the drive axles a mile down stream from the scale. I could have slid the trailer axles forward and/or the 5th wheel but the truck rode SO much better stretched out so I left it.
