This is true and not true. They are all spec'd at 18.5
It is always true. The tank capacity is not conditional. They are all 18.5 gallon tanks.
If you or someone else has issues with the fuel pump, fuel gauge, fuel level sender, (There's a TSB for '99-'00 models) evaporative emissions system, vent hoses, etc., none of that changes the capacity of the tank.