Sounds like you are referring to the newer style (1994+ in the US) integrated traveler track in the rear beam. It takes a different traveler car (Hobie US Part No. 111) than the older style. See the lower right hand portion of Page 52 of the catalog. Near the top of this area is a small drawing of the cross-section.
http://static.hobiecat.com/digital_asse ... _Parts.pdfI believe that the only difference between old and new styles is the lower roller unit (Hobie US Part No. 112 for the new style). The newer one has brass rollers/smoother action, and I think the older car will fit the newer track, just not perform as well as the newer car. I don't think the newer car will fit into the older style track.