I drive those everyday at work to pull bombs.
It's a bobtail. They are 3 speed autos, 7. 17 gears. They'll do about 35mph. The newer ones (late 90s) will do 40mph. We had a few 2000 and 2001s in AK. All the Dodge we had were 4x4, put them make them 4x2 as well.
Pull tandem trailers that weigh about 3k empty, loaded with 4 2000lb bombs each so ~22,000lbs. The trucks weighs like 10000lbs. There's big slab of steel under the gas tank, plus that bed is 1/4" or 3/8" depending what part of it.
They made Chevy versions, duallie, Ford duallies (85s with the 300 I6), CJ10A Jeeps, 7. 3L Fords, 6. 0 Fords.