Mike,  The tanks are held on my brass tabs bent over to hold the tank all
way around the tank.  If the tabs can be caught then pulled open,  easily,
the tank and the rubber gasket behind it should come right out.  As far as
the plastic ends, I work with fiberglass resin all the time.  If one coated
the tans before trying the removal, it should hold it intact without
breaking them.
Thanks, Lyle