Rear Reverse Leaf Overload Springs?? Factory or Not???

[milehightoyz]

hey guys, upon installing some drop coils on the rear of the 72 burb i just picked up, i noticed a reverse overload rear leaf spring on the rear of my burb. it appears to be factory, but i dont know?? ive not seen one before, just wondering if this is a factory option or an aftermarket piece? im gonna yank it off, cuz i dont need it, but im just wondering if i should keep (if its rare), sell(if its worth something) or toss in the dumpster(if its worthless)?? i threw in a pic of that gas tank that i swore was plastic but looked factory as well. also a pic of what looks like an attempt at some cheesy home made lowering blocks, the funny thing is they are in the wrong place?? could they be home made shock relocaters??? haha. anyways, i dont know if i got something rare here or another case of backyard engineering?? any input is greatly appreciated.