[Troy Sr]

Originally Posted by SS Tim

Gary, Your truck probably had a pair of in-bed tanks. Most of the aftermarket saddle tanks used side doors (including the GM accessory saddle tanks) or wheel well fillers. The really high through bed fillers are usually only seen with in-bed tanks. But the GM NL2 and earlier N18 aux tanks did use a similar left side only with a vent pipe style filler.

SS Tim,

Mine had the factory option tank and it also has the filler in the same location, there's a sheet metal cover in the bed that hides the tube going through the bed and up to the filler hole.