There are only about 8 (?) manufacturers of replacment leaf packs for XJ's
Tomken 4", 6" lift
RE 4.5"
OME 3"
(C)Rusty's 4.5", 6.5"
Rancho?
Skyjacker 6"
RK 4.5", 6.5"
Full-traction 6"
This does not include custom made springs from the likes of Alcan, Deaver, ect...
Most are pretty proud of thier products and will have some sort of markings on them, RE and Tomken use a white stenciled markings on the top of the main leaf.