Don't worry about new or used, works the same. It's not technically new. Rebuilt and painted. Order from ebay guy but be ready to tune it. There are tons of threads on this, you may search and find a lot of useful info. His product is good, support and "pre-tuned" settings not so much.
89 YJ 4.2L http://www.jeepforum.com/forum/f12/kgb-89-yj-storyline-build-thread-1520814/
96 XJ 4.0L http://www.jeepforum.com/forum/f177/600-96-xj-budget-daily-overland-build-1855418/