Like the above poster has stated, parts for the P30 chassis are very plentiful and cheap and since you're looking at a non tag axle rig, even better. The tag axle was an Airstream exclusive bit that for a while were very scarce.
As for the rest of the unit the only part that I know is impossible to find is the door lock; there is a replacement lock mechanism but requires some patching on the door as the new lock is smaller. Keep your lock well lubricated and it should last as it's a very heavy duty unit.
As for everything else, the skies the limit as you can replace the old air compressor with a new one or get a rebuild kit.
You can buy new front fibreglass lower sections, vent covers, etc, etc.
Per Mare, Per Terram and may all your campaigns be successful.
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