I would think that removing the tank would be overkill. Imagine your disappointment if it had a quart of clean Diesel in it.

I think I would open the drain to the tank and run some fuel into a clear jar and look for signs of algae.

If there were, you could hit it with some algaecide and add a bit more fuel. If it had no algae you are probably good to go.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)