Looks like you got a good start on the tear down, also a nice pile of parts to start with
Drivers side spring was replaced or reworked at some point , check to see if it is 2" wide , passenger spring appears to be original
The bolt appears to be the spring center bolt, may have been placed there for safe keeping.
Most of the bolt I encountered I used a torch or grinder to remove, bolts are cheap, and will be replaced anyways/ best place I've found for hardware is Tractor supply sells grade 8 bolts $5 lb ,
Cheers from Mesquite,
