I'm not familiar with Dish Traveler. But the lnb you get depends on the dish itself. A starting point would be "eastern arc" or "western arc" search but again you'll want to make sure it is compatible with the dish you have. It also depends on where you are in the country. Eastern arc is further off horizon on east coast. Same thing for Western on the West Coast... So more likely to get a better line of site. If you call or email the stores that sell them, just tell them your setup and they can likely put you in the right direction.
I expect the OP is referring to Winegard's Trav'ler automatic aiming roof mount dish. The Dish version is basically a 1000.2 dish equipped with a western arc DPP LNB. If the Trav'ler was previously used for DTV service, it will need a kit to update it for Dish use. The correct Dish DPP LNB can be found at a number of online sources, including Amazon if a replacement is all that's needed.