I registered for this forum just so I could give a definitive answer to this thread. After much pain in trying to figure out this exact same problem for myself (bought a used Rebel where the previous owner took off the rails before selling it), I can give the proper part numbers for this need.
The part number for the rails needed in a 5'7" Rambox bed for aftermarket tonneau tops (the rails have a track on top as well as the main track for tie downs) are 68027048AD - Rail, Right, Cargo and 68027049AD - Rail, Left, Cargo
Unfortunately, I found out the hard way (because I ordered, and subsequently returned) that the part number for the rails used with a Mopar hard tonneau top (the OP's rails) are 68171744AD - Rail, Right, Cargo and 68171745AD - Rail, Left, Cargo
The above parts are for a 5'7" Rambox bed. The 6'6" bed rails for aftermarket tonneau tops would be 68084030AB and 68084031AB respectively for the above. The part numbers for rails with Mopar tonneau tops on a 6'6" bed would be 68171746AD and 68171747AD
I'm really not sure if Ramboxes are made in 8' beds or if either of the rail types above are made for 8' beds.
Incidentally, Mopar's diagrams and descriptions that are used on most all online parts stores are total crap. If you plug any of those above part numbers into an ebay search, you usually can find a seller that has put actual pictures in the ebay listing.
Thanks to the posters of this thread as it eventually helped me determine the above information so that I could put on a BakFlip cover. As an aside, I may post a follow-up comment depending on how well (or not) the supplier I used comes through with my exchange (moparpartsoverstock . com or dodgepartsoverstock . com... same supplier). They show a policy of an outrageous 35% restock fee, but the guy on the phone seemed like he was treating this as an exchange and not a return. I can understand up to 20% restocking, but 35% is crazy.