I hear you. I fabricated brackets to mount an aftermarket tank behind the rear-end. I modified a steering wheel bezel so that the filler neck is on the rear bumper, and converted to an electric fuel pump. No issues.The 1984 k-10 donor chassis has tank under the rear frame. I added a larger tank. a secondary electric pump and soon a tank shield.
I retired as an engineer with expertise in hydrocarbon/gas monitoring equipment. Tested many in cab tanks using a hand held, volitile organic airborne tester with .10 ppm detection. Calibrated for benzene (primary gasolene component and well known human carcinogen) results were scary. Even with all brand new components in cabs leak vapors. Most leaked well above the absurdly high 1 ppm exposure limit. They now sell inexpensive versions of these meters on ebay so heads up
Nice. Mine is very similar but on the other side. Filler on the tank was on the right side.Smart to move it. Been around gasoline my entire life and didn't know how bad it was until getting a MS in Toxicology from UC DAvis. Amazing how the petroleum industry buried the hazards all this time. (and continue to do so). In any case the filler neck is now at the rear of the drivers side fender just above the taillight per the pic. Set it up so can rest the nozzle while filling as getting weak hands. Formed a stock 84 k10 filler hose and breather and altered frame to fit. Very handy and not like a PITA in bed filler.
It was a billet aluminum bezel from a Grant aftermarket steering wheel. Somehow I managed to have an extra one, and I realized by machining about a sixteenth of an inch out of the center, the filler neck would tightly slide into it.Where did you get the trim ring? looks great.