Re: hub centric wheel adapters?
There is a hub centric spacer, not just for getting the right bolt pattern either. Standard 5 on 5 hub centric spacers can be found all over. Hub centric simply means that they are machined from the hub ring out for a very tight, very exact fit that prevents wheel wobble and premature bearing wear. Don't buy the high end name brands, check out ebay first for "5x5 hub centric spacers" and you'll see a bunch of high quality machined aluminum spacers (just check user feedback). I came from the Wrangler community for the last 10 years, and am very familiar with using them. For daily driving, they're okay, I really don't agree with using them much in rock-crawling or high-horsepower applications, but for a regular ol' GC, they should work fine.
5x5 bolt pattern is the same as wrangler, but you might ask about the hub ring fit itself and how universal it is for Wrangler/GC. I'm new to this GC thing, so I'm still getting acquainted.