Auxiliary gas tank question

[scottd03820]

Hello,
I recently purchased a 1975 gmc swb. I'm going to restore the truck and have a question. The truck has the standard stamped steel tank on the passengers side but it also has a square steel tank on the drivers side. It doesn't look like the passengers tank at all. My question is, is this tank factory, a dealer installed option, or something one if the previous owners installed? Any help is greatly appreciated.

[Billy81]

I had two trucks with those tanks on them and i seriously doubt they were factory or a dealer option. My old 81 C10 had one installed by some RV place and they did an okay job installing it but it never worked right. My C20 had the same tank but i am not sure who installed it but they hacked up the bottom of the cab to make it fit. The gas filler was in the rear wheel well and was a royal pain to fill it up and prone to getting damaged.

[scottd03820]

Thanks for the response. It is a clean install but the filler and cap don't look good. I'm thinking of taking it out and welding the hole.