"Your biggest ongoing battle will be chasing air leaks, especially in the aux air system relating to the suspension. Yours is sensitive to that because once the aux air drops below about 35 PSI your rear air bags will dump air and the coach will drop"
I agree with Jon on this but there is a solution to the tag axle lifting when the aux air pressure drops. They knew their mistake.
Prevo has a service bulletin I have linked to it here. They call it tag axle logic or something like that.
If you are planning to replace much of the suspension components and you have a bus that does this you should open this PDF check it out.
If you do it while you are doing the rebuild it will not cost squat it is mostly re plumbing the 3 port 2 position spool valve opposite of what it currently is. They even give you a new decal for the air toggle switch to remark up to down and down to up right in the kit. The entire kit from prevo concists of nothing more than a bunch of different fittings to plumb those spools 180 from where they are original.
If you have the ability to R&R suspension stuff you can do this too. If you do decide to do it it will also give you a way better understanding of the suspension system and how it works as well.
The signal air for that spool between the drives and tag that releases is aux. air so even if your brake tanks stay up the tag will still raise when the aux air drops. This eliminates that and makes the bus the way they currently plum the tag lifts.http://api.ning.com/files/iWAEFc41PyR93QmtwRc6HkEM9QrxtsX0uQrBCVXhqSaF7qBOmPLr-xAH0pLVVfu3J4nesHxVq3MWq2o18WWzsJmOtcRhkZ7I/PUB96ENG1.pdf