XLT denominations were not available on the '02, I think they're on '03 and newer.
I have an '02 Premium package ST, no big problems so far. I guess that standard caution should be used like with any used car. I don't trust Carfax, if you have a trusted mechanic to check the truck before buying would be a good idea.
There are several reports of Transmission failures, some requiring a complete rebuild, smaller issues are the DPFE sensor, crappy shocks, and several more that you can catch by reading the board messages.
So far I am very, very happy with my ST.