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Sure, in 90% of the cases, alternators can be overhauled. Still plenty of old-time alternator repair shops around.

You have to pull it out anyway. Take it in to a shop. If rebuildable, great. If not, that is when to decide to buy a new one.

Have you gone though a complete diagnosis to know that it is a faulty alternator rather than something like the battery isolator or poor connection for the sense wire, etc?

Looking for some help.
95 Sahara, 5.9 Cummins, propane generator, M 35

Seems the chassis battery is not charging, house batteries are charging.

Have to push the boost battery switch to start it. Looking for the battery isolator switch, where if it has one?
Also has only one chassis battery

The battery isolator (either diode-based OR solenoid-based) only, repeat only applies to charging from the alternator.

You may (or more likely may not) have a means of charging the chassis battery from 120 VAC. There was not one originally on your coach.

If (OK, big IF) your boost solenoid is a constant duty one/switch allows constant on vs must hold down, yes, that will allow the chassis battery to be charged by whatever device charges the house bank from 120 VAC.

Many of the safaris came with one or two 45w solar panels, to help maintain the house battery bank if parked in outside storage. If those panels still put out power, I would suggest connecting them to the chassis battery bank, instead of the house battery bank, or install a similar device as an echo charger. To charge the dead batteries in the mean while out camping, either connect a battery charger to the chassis battery bank, or connect booster cable to both battery banks. Obviously disconnect the booster cables before driving off...