I have a 2006 Grady White 232 Gulfstream with two fuel tanks, Aux and Main. Mechanic is telling me that the Aux tank is leaking fuel, based on it is 19 years old, aluminum and has a small stress crack. What are my options for and your recommendations? Can you buy new tanks off the shelf to replace, or replace with a custom fabricated Tank? Worth trying to find a certified welder who works with gas to fix or this just as expensive with a risk of a future issue? Thanks in advance.