The heater come out and go in from the outside. In my case I had to trim the exterior skin a little to clear the new heaters insulation when installing.
Other than that it is a straight forward install.
Are you sure the leak is the tank? Unless the heater was not drained at all the water left in the bottom f the tank should not split the tank because of the curved sides.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles