TV upgrade or downgrade?

I'm currently pulling a 5K lb Jayco with a 2007 Silverado crew cab (5.3L, 4 spd, 3.42 gears) and feel the TV is under powered, expecially when I hit a moderate incline. I'd like to step up to a 3/4 ton gas or diesel eventually but it's not in the budget until I get the DWs Explorer paid off in a few years. My uncle has a 2000 F350 crew cab with a 7.3 he purchased new (over 130K miles on it) and offered to sell it to me well below blue book. If I took the offer, I'd have to sell the Silverado (it's paid for anyway) and use the F350 as a daily driver. What are your thougths? Would you sell a newer TV for an older TV with more miles? People say diesels last much longer with proper maintenance but the age of his TV is making me think twice. I'd probably drive the F350 for a few years until I could swing the payment on a new 3/4 ton.