[superbirds]

1975 Newell - Ride Rite rear air spring - Normal pressure

I need to back up a little to explain this. When I picked up this coach I noticed the air pressure on the dash showed around 90 psi after running for several minutes. I found a line that came from under the dash connected to the brake switch "parking plunger" that was leaking or regulating I'm not sure. I found a new one and replaced it now the line maybe a waste pressure release port. Currently it is not leaking or regulating and the line pressure is running around 120-128 psi. I replaced the unit with the same number, also looks identical.
This has caused the rear of the coach to sit higher then it originally did. Looks a little too high to me. 
I can adjust the regulator on the engine mounted belt drive compressor, however it doesn't go much lower then 120 psi. 

This has Firestone air springs quantity = 4.  Two on each side front and rear or the axle mounts. The front suspension is standard leaf springs no air springs. I also plan on inspecting the rear bars/arms the rear air springs and shocks attach to. My thinking was to get it cribbed up with wood blocks and 20 ton jack stands then get up close and personal with the rear axle and air springs.

This coach also does not have a leveling system when parked. They may have used ramps or wood to level it, not sure. I did run across someone selling a hydraulic 4 shock/strut system. Looking underneath I'm not sure how you'd mount it. My crazy idea was to use the rear air springs with a aux 12v air pump. 

I suspect I either need to adjust or replace a pressure regulator for the rear air springs. I've done some searching online, but really have not found anything that gives a range for this setup. I've not called Newell yet. since it's such an old unit, I thought I'd ask here first to see if anyone has any thoughts.

Thanks in advance.