75 Chevy SWB 4x4 adding a saddle fuel tank on driver's side

[75 Chevy SWB 4x4]

I just got this 75 Chevy SWB 4x4 and it only has a saddle tank on the passenger side.

I already bought an OEM fuel tank switch for the dash.

Can I just add the fuel tank switching valve, some wiring, left 16 gal fuel tank with sending unit and straps, and either cut a hole in the left bed side for the filler neck, or find a stock bed side that already has the fuel tank neck hole in it? I'm sure someone else here has done this task, but this is my first square body Chevy pickup that only has one gas tank.

 

[Tank6x2]

It all sounds good to me, can’t think of anything your missing…

 

[75gmck25]

It’s a relatively easy mod once you get the parts. The fuel filler hose is not very flexible, so it has to match the filler setup (hole in bed side versus door). You need a 6 port or 3 port fuel solenoid, and matching wiring and dash switch. Original setup used sections of metal line running across between tanks, and then short sections of rubber hose, but all rubber hose will work.

If your truck has a 3 port fuel pump with a return line, you will need a six port fuel solenoid to switch both fuel feed and return. The original Pollack six port from the mid seventies (only one electric terminal) is not longer sold, so you need to use a six port with a multiwire electrical connector. The original 70’s 3 port Pollack solenoids with non one terminal are still sold, and work if you don’t have a return line.

I added a 2nd tank to my ‘75 GMC and was lucky enough to find a complete setup to pull from the junkyard. I wrote up a couple documents I could post if you want more detailed information.