The 318 must be the same one that is in our 97, they used that in all Dodge trucks, the Durango also, it has a lot of torque to pull, but when I am pulling the camper thru decent size hills, I disable the overdrive when I get below 50 mph, otherwise it starts to slow down.
Ride wise, I think yours have a lot nicer ride than mine, the 99 and newer feel more like a car ride, mine feels like a truck, I think also the 4wd adds to the rough ride, specially when turning the steering wheel.
The 99 front suspension is almost the same as the older ones, on the rear suspension I see slightly different setup.
I get around 15 mpg pulling the hi-lo which is decent for pulling that much weight.
oh one thing I almost forgot, on my 99, the electric fan and/or fan relay kept going bad, didn't stop completely but you can see it not pulling fast enough to cool, but it was easy to fix and relatively cheap on the parts.