No problems at all.
With only 3,453 mile on the odometer, this GT is flawless with everything original except the battery. The tires are original and in excellent condition. I did change the thermostat and replace the bypass hose. She is garaged, covered, and taken out only on sunny days, early when there's no traffic, and driven at least 15 miles on the freeway. Oil and filter is changed every 3 months and the leather seats are conditioned with leather balm. The radiator is flushed with distilled water and replaced with a mix of anti-freeze and distilled water once a year. The white GT hatch shares the garage with her sole mate, a 67 white coupe with 82,000 miles on the odometer and also original right down to her Ford Diamond Luster factory paint and factory air. They are both showed in the unrestored class and have never taken less than first place. I hadn't planned to baby the 90 GT. as the 67 was the show stopper, however things happen and you just get attached to them and a short drive now and then is just fine. They are just great to look at parked side by side.
I absolutely agree with you, the Mustang is now and always will be an American legend. Between the 1990 and the 1967, without a doubt the 67 is the more classic of them, however they are both pretty sweet cars. The only thing is when looking for a mustang be VERY sure that the car is in good condition. People love to beat on these things. or at least that's been my experience.
I used to like the newer 94+ style mustang's looks, but after seeing those 87-93 style up close and after driving it my mind is changed and I like that style almost better than the oldies from the late 60s. You got some nice cars, take care of them.