Welcome to the site. There's a lot of GREAT people here!!! I just bought a 350 PSD 4+4 dually this summer. I have a 22 ft travel trailer at 7,000 lb and it don't know it's hooked to anything. Mine is also an early 99 with 147,000 miles at this time. They are a lot of truck and as far as pulling I don't think there's anything to worry about. Good luck on what ever you decide.
99 Red Stroker