I picked up a set of Saab roof rack off eBay. It didn't come with any locks at the rack end-caps (I am not sure what you call them but they are the black plastic caps at the end of the track, there is 2 on each track so I need 4). Was wondering if anyone here knows if the Thule lock cores fit? If so, could someone advise part/model number of the lock cores please. Which other types/brand of lock cores will fit?