Fuel fill through rear fender well?

[SS Tim]

You are talking about the very common accessory/aftermarket saddle tanks added to most (it seems) C20-30s. Even the factory NL2 aux tank was pretty much the same. An often seen variation was the fender well fill (vs cut doors). Demco is one brand that comes to mind as using that style filler. The soup cans worked well at keeping grit off the filler but that area would pack with snow/ice on occasion.

Finding a tank or a pair used shouldn't be a problem. Either usable or as patterns. Tom probably has a set or two there in Mesa.

The other alternative is to install the NL2 tank installation on your truck as it would easily backfit. But the through the bed filler (Blazer style) is off-putting to some.

The 73 up tanks are designed to use a frame mounted cradle bracket and extend under the cab floor that is raised to allow the tank to nest. To me its not worth the effort given all the bolt ins around.