I would it say it depends on how many miles and how long your keeping the truck. I keep mine about 10 years or more. I've always come out ahead, even on my 98 Caddy SLS. It needed all new struts at 23K and 4 years old, very expensive. It was covered thankfully. I think they were $500 or $600 (dealer only parts) each, plus labor and some rubber bushings. I paid 1K extra, it would have cost at least $1500.
Things have tended to start having trouble between the 5th and 6th year, or for me 50 to 60 thousand miles. Then its smooth running. The dually is used for hauling and pulling most of the time, so more miles will be under load than not. All my Dodges have had Autos and they all leaked and shifted like crap. One front seal cost around $540 on my 98 Ram, it was losing enough trans fluid to wet the bottom of the truck to the point of it dripping from the frame drive shaft etc. The added coverage is really nice when you need transmission work! The dealer charges just under $400 for those weak track bars, I went Moog instead. Power windows have been an issue over the years too. The 03 has a problem right now, The window rattles and bangs the glass when raising. I don't like messing with that stuff.
Our truck has had more problems than the average truck, its been back to the dealer more times than I can remember. Its nice to know, if the A/C fails 5 years from now, for the 5th time, the dealer will fix it at no added cost to me. I've already had the compressor changed. Now the 98 was just about problem free, only went to the dealer for one recall and two service visits, track bar and transmission. The water pump just went out probably because it sits too much. I wish I had gotten more than the 5 year plan. So far, its paid off in our case. Usually I don't have the $$$'s for a new trans, or new computer, or new trans, they tend to fail at the worst times. :{