AL Wtb axillary fuel tank retaining nuts

[Fourbrads]

Thanks. That helps. I'm guessing that the sides of the shaft portion of the old flange assembly are rusted to the insides of the through holes in the tank. And you're right....there is a lot of crud in there that has accumulated over the years. I'll have to find a way to pick that stuff out first.

My plan is to clean out the through holes as best I can, seal the holes in the flange bottoms, then pour rust remover into the holes and let it sit. With any luck, some will creep down the rusted sides and loosen it enough for me to pound out from above with a pipe.
Appreciate your help Sir.