Do you need the rubber hose that goes between the fuel tank and filler neck? If so, this is the only place to get the right part:
Filler Neck Supply Specializes In Fuel Filler Necks & Gas Tank Parts For Utility Body & Flatbed Conversions, As Well As Radiator Filler Necks, Secure Internet Checkout!
www.fillernecksupply.com
If you need the filler neck that attaches to the pocket behind the fill door make sure you get an 87 or newer filler neck. They redesigned the vent for the fuel tanks in 87 to prevent the fuel pump from always clicking off.
Use this search engine to find a truck in a salvage yard near you.
www.car-part.com
BTW, I'm north of Edmond, OK. I might try to make it to the Coffee and Cars with my truck on the first Saturday of the month. It's at the Life church parking lot on 178th and Penn in OKC. I'm not sure if it's going to happen next month though because that's 7/4/26.