very similar to what i saw / experienced.
I was pulling often and my 98 1500 4x4 dodge with a 5.9 gasser was 1, just not HD enough, 2, wasn't super fuel efficient. not sure on the rear.. felt like near 3.73 or simial.. don't remember now..
I sold it and got a 99 f350 4x4 drw with a 7.3psd and 4.10 rear.
I have MUCH more tow capability, stability and breaking power. I get no worse fuel economy.. maybee even better. Acceleration? ok.. the 98 gasser , EMPTY took off a bit faster thant he PSD.. but loaded.. the psd sucks the doors off the 5.9 gasser...
service costs are NEAR a wash. I was doing 3k oil changes on the gasser using walmart oil at 6qts plus filters.. and 8500 on the diesel using a good synthetic at 15 qts, plus filters.. no spark plugs or wires or any ignition stuff. the diesel, per year.. may cost a bit more on the service.. but if so.. not much.. enough to call it a wash..
I can't see NOT keeping a diesel... especially if you pull a trailer or have large loads in your bed.
I had to go pick up a buddies broke down full size conversion passabger van out of south georgia a while back. blew down the interstate to get it.. and ran a lil slower onthe way back. the old dodge would not have done that for me...