Hmmm....well, while I'm not an absolute Trek expert, I don't recall any of them coming stock with anything other than clinchers. The only rims that I can recall that were dubbed "GEL" was the very light Mavic GEL 280, a sew-up rim which really was used to build straight up race wheels, at approximately 280 grams per rim. At the age they are, plus the fact that they have been outside for an untold amount of time, I'd cut them off and do a rebuild with new rims..or get a nice used vintage wheelset for it.