[Early Rider Steve]

We called them saddle tanks back in the 60's-70's. The right side tank was hard to fill with a camper, my Wife would have to stand and block the island so I could turn the pickup around to fuel the right side.
On my LS swap I'm keeping the left side tank, and have it hooked up to an electric fuel pump. Going to use it to transfer fuel to my new rear fuel tank.