Today I used Marine Clean and a scrub brush on the exterior of the fuel tank. I wanted to get it clean so there was no chance of dirt falling inside the tank while I did the Prep and Ready and sealing stage. I put two tarps up by the garage door and set to work.
The fuel tank cleaned up pretty well with the Marine Clean and I got a better look at what I had suspected was a patch. There is a label on the tank that reads "Fresno Radiator, Fresno, California". The patch looks to be made of either brass or copper. It does not leak though so it must have been patched well.
Here is the bottom side of the cleaned fuel tank. There is minor surface rust but nothing loose that needs to be wire brushed off before I can paint it with POR-15.
Here is all the dirt that came off the fuel tank. Notice the flower pot on the tarp - it worked well again to seal the opening while I was cleaning the exterior.