Well they where mad back in the 70’s by a co. called California step side. They where basic looking to start …one style fit all but just moving the bed rails under the bed to the mounting points on the truck then sitting the bed on and marking where to weld them… then they became very popular with the mini truckers … and 2 other companies started to make them on in Florida and one in Texas not sure what the beds where made of from these companies but they used Chevy or Ford fenders from late 50’s early 60’s
Then Chevy got the idea of having a bed designed for the luv and had I believe the nephew of Barris design the fender for the bed… and that is the one we see almost all the time on the luv, this made it a dealer option (not factory) that could be sold as an upgrade for the luv … here in Oregon I would go to the dealer and for every 10 luvs they had 4 or 5 would be step sides new but not from factory seeing how it was cheaper to import the luv with out the beds on the truck (less tax) and then the dealers would install the beds weather fleet or step side this also explains why there are more step side luv’s then any other import truck… as a side note there where a few 80’s step side made that where all fiberglass for ford and Chevy but not sure who made them
this ends the class of step sides 101 
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My old but now gone Luv...
