Suburban cut outs (opening size) is completely different then Atwood cut outs.
Dometic makes a 'KIT' (brackets) to replace a Suburban with an Atwood
Conversion KitCourse you will still need to modify/run new wiring
Suburban Electric/Gas have separate systems (unless it is a DEL model)
120VAC is direct and 12VDC for propane
Atwood uses 12VDC for both electric and propane controls..so will need to change the wiring and provide for DC to turn electric on/off
Not real difficult just more involved then pulling old out and installing new.
Leak from inside combustion chamber.....
Poor factory welds (over heated where the spot welds are for baffle plate)
Condensation from flue gasses cooling

Anode rod....
Check the head of current rod
Smooth.....Aluminum
Bump in center...Magnesium
IF aluminum...it is NOT protecting your water heater as evidenced by it still being almost fully intact.
That Atwood XT Model.......uses a mixing valve to 'extend' available hot water.
Water is heater to 155*F (t-stat set point) then cold mixes with hot and mixing valve controls output to 130*F