You can find a good used Ford F250-350 gasser for cheaper. Especially in Texas and most are in good shape with little to no rust. Can pick up a 12v Cummins motor for around $1000-$2500 and it is a EASY swap into a Ford.
Although, I like the older 12v Dodge trucks myself. I've got a 98 12v with 334,000 miles and when the motor was taken out for a rebuild at 323,000 the main bearings looked almost brand new. Nothing wrong with the motor at the time, I just add lots of god fast goodies for racing and sled pulling. 98' is retired from ranch duty. The 98' towed most of its life. I just recently picked up a MINT 96 with 160,000 miles from and old couple that used it to towed the rv and boat they had. I only paid $8500 for it. Look in the southern states and you'll find some good deals! RV'ers are always selling good trucks in the south for decent prices. Dont worry about the Cummins with an Auto. In stock form with stock power and regular service they will last a long time. Excessive heat will kill an auto though, believe it or not, Dodge has a GOOD stock cooling system for the autos in the diesel. If power is increased I highly recommend upgrading the auto trans with a good builder such as HTS, DTT, Geroend Brothers, Suncoast. AVOID ATS! ATS makes great products but the tranny's they build are junk IMO (personal experience). I run a fully built DTT in my 98' and towing setup in my 96' and have had zero problems. If the CTD route is one to take, get the 4x4 Posi-Lock kit for the front axle. Just my .02.
Daniel