[72SB]

OP

You can look up what a 72 LB is selling for on Hemmings, ebay, etc that are comparable condition of yours to see what the "market" is now. C10's are "popular" now and have been so do bring a little more $.

SB typically more than LB given everything is =

While you are candid about rust in doors and drip rail...that can be a hit on $

I don't want to say how much but I would think $20 would be the neighborhood +/-. List it for the higher $ and go from there but IMHO just look up comparable for a more accurate current market value