I did the same fuel door install from a Tahoe. I cut a square out of the side of the Tahoe about an 1" bigger. Cleaned it up, transferred that size to my bed side, cut that out and welded in the donor door panel . Came out great.
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Sold the 63 and have a 68 now.
63
SWB C10
LT1/4L60E, PS, PB, Disk Brakes, CPP 4" drop coil rear, 2.5" drop spindle w/ 1" drop coil. slotted rotors, front and rear sway bars. 18"x8" Cragar SS w/ 245/45R18
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