Great IDEA with the shop vac Leathermang! P.E. I looked inside and the fungus/algea never adheared to the sides or bottom of the tank. It just looks brownish in color but no black on the inside metal. I think that is normal for being soaked in diesel for 25 years. So, I'll just spray it out and dry it off and put in the new sending unit and fuel strainer. Thanks as always for the help.
My friend has a shop hear and we ended up welding a bolt and 7/8in nut together and it backed the strainer out pretty easily, I quess I was just using the wrong tools for the job, go figure.