I've gotten them in the past from RCP Crawlers, but they don't have them in stock at the moment. I hope they will soon though, I'll PM them on RCC and see what's up.
http://rcpcrawlers.com/product.php?productid=847
Also, here's a product plug for RCP, they make some killer R&P sets for the TLT/semi axles.
http://rcpcrawlers.com/product.php?p...&cat=17&page=1