truck sitting 24 years, cleaning out fuel tank

[mike16]

my 68K20 has 13k miles on it. its been sitting for over 24 years. the current batch of fuel in the tank is al least 1 year old. I dont know how much is in there. but I want it out befor I put fresh gas in and start it up. what has any one else done to remove the old gas. what solvents work to remove the shellac that no doubt is also in there.

Also... I have saddle tanks that I can tell are much worse in terms of old gas.

So how to remove old gas... and how to clean tanks.

I want to avoid actually removing any of the three tanks.