Suburbans have been know to leak at welds on divider plate in the combustion chamber
If that is what is leaking ain't no 'replacement' parts. Welds penetration was too much when built
Tank is steel/glass-lined and are NOT replaceable....nor can be rewelded
Whole NEW water heater required
Not from inside the combustion chamber....
Is it from T&P as outlined in above post ----'weeping'
Is it at/around combustion chamber?
Then check for leaks on backside of water heater ....cracked fittings/pin holes ---they can cause leaking around the combustion chamber---pass the seal rings