Look at it this way........
Suburban uses a steel tank that is glass-lined hence the need for anode rod.
Residential WHs are built the same--------have you ever gotten 17 yrs of use out of a residential WH?
And then take in consideration the bouncing/jarring that your current RV one has gone thru.
Even if you replaced spark/ignition control etc. you still have a 17 yr. old glass-lined tank.
Time for a new unit.
Suburban 6 gallon will fit where a Suburban 6 gallon was.
Same with 10 gallon etc. provided it is same Brand
Suburban swapped with Atwood---------different openings so mods to exterior of rig would be needed
Now is a good time to upgrade to newer and go combo (electric/gas) if OEM isn't already a combo.
17 yrs....you got your monies worth