Hello butch 58, and welcome to irv2!
I suppose there is always something to worry about on any used rig you buy, but don't let that stop you.
As with any model you buy, see if you can find someone local (and trust worthy) to do a pre-purchase inspection of the unit. Most people in the Gulfstream owners forum will agree the overall quality before 2002 at GS was good. Cutbacks in the industry in later models can cause possible quality issues after that.
Obtaining proper maintenance history is a must, otherwise you have to assume the coach had not been cared for properly.
Be sure to get the date codes on the tires, anything older then 6 years will need replacement.
Others will probably post with tips I have missed.
'98 Gulf Stream Sunsport 325, 7.5L Banks Power Pack, Koni FSD's, Air Bags, ReadyBrute Elite,
2000 Honda Accord