you can buy a round carrier for a lt500. It uses all the stock components. im thinking lonestar? I had one in my old leagers arm. If I was you id get a arm for a banshee carrier. Best thing I ever did for my 500... Then go on ebay and buy a banshee axle assembly on the cheap...
There are a few companies that make the LT-500 round carrier. But if you are drag racing, definitely go with the Banshee size carrier housing and run an aluminum axle.