We have an '02 GT 325S. I'd suggest a careful look at the blade seals on both slides, as they have a tendency to roll over and also at the bulb seals on the interior walls that the slides push against when they're fully open. The adhesive FR used back then tends to let go as it ages. The blade seal issue is easily fixed with a dry-lube like graphite or moly. Peeling seals can easily be fixed with 3M weatherstipping adhesive. The risk is that they may have been deformed or peeling for a while. If the rig is on the dealer's lot with the slides deployed, the upper blade seals could have been letting water in for some time.
We had rainwater in the overhead cabinets in the living room slide because of the blade seal problem. We got a mold infestation in the woodwork and I had to build and install replacement cabinets.
Based on our rig, my only complaint is the less than stellar quality of the cabinetry. I'm 5' 10" and don't notice the ceiling height as a problem.
Of course, check the age of the tires. Ours had 12,000 miles on it when we bought it in July '10. The tires were Goodyears and were the originals for the '01 chassis, and were dated in 2000. We changed them after just a brief shakedown trip.
Be ready for a ride quality that reflects its truck heritage. This is normal with the F53. It is an 11-ton truck, after all. We've decided to spend money on gas and CG fees rather than trying to make it ride like a Rolls Royce. The old proverb about silk purses and sow's ears applies.
Frank and Eileen
No longer RVers or FR owners