Here is some information I hope is helpful:
Would need to verify, but apparently these part numbers are direct replacements:
3558186RX CUMMINS Direct Replacement
3558186NX CUMMINS Direct Replacement
3558186PX CUMMINS Direct Replacement
3558186 CUMMINS Direct Replacement
Haldex most likely has a rebuild kit:
Cummins C-Series - Type QE296C
Links listing compressor for sale:
If you can't get a compressor on the way and installed soon, you should consider getting an electric compressor and hooking it up so you can get home. This has been suggested earlier on in the thread and it would be easy to do. You have plenty of volume tanks for storage and you will not consume much air doing any normal driving. It would take a bit longer to initially get the system up to pressure, but it should keep up fine with the air suspension and brake usage. You could plug it into a receptacle in the bedroom, run the airline under the bed and connect it to the air system by the dryer. This connection would be similar as was done when the dryer was bypassed. Another option would be to connect it to the port in the front left compartment which exists for a tow truck to feed the air system if the coach needs to be towed. An airline could be routed out the drivers window and into the compartment, and taped onto the body so it's not flapping in the wind. Personally, I would go the bedroom route so the line could be more easily secured. This would get you back home and you could have the repair preformed in a local shop.
Good luck. I am sure you are beyond frustrated, but this will get resolved soon. You have a great coach which just happened to develop an unusual problem and you had the perfect storm of ending up with every unqualified mechanic in the state some how. I hope you get it going soon.