Jerry, Best 1/48 A-10 is in fact the Monogram A-10 from 1989. Tamiya does make one, but it's based on a prototype Aircraft and so some of the dimensions are a little off. Hobbycraft has one out there that's pretty easy to find, but it's a horrible, horrible, not just kinda bad, but really BAD kit. I think there's also an AMT-ERTL offering who's main highlight is the included USAF ground equipment that comes in certain boxings, but is otherwise innacurate as well.
The Monogram kit isn't too bad right out of the box, although it does have some seam issues and raised panel lines (but looking at reference photos, if you could ever make a case for raised panel lines being prototypical, the A-10 is that plane.) There are several build up reviews of it at Aircraft Resource Center. I've just started building mine as well, based on one of the aircraft of the 303rd TFS based alongside the B-2's at Whiteman AFB, MO.