h2 air suspension replace compressor ?

[andrew&melinda]

2006 H2 64K miles - air compressor looks like later dual unit
Service message on dash, no apparent leaks.
GM dealer checked codes error is C0716 they suggest risk changing valve suggest complete new unit part 89060581 @$1649.00 plus labor.

Drove home to decide what to do - seem to have lost some air when dealer did tests so down some, more on passanger side.

When ignition is on unit trys to work, both units cycle (noise / you can feel each vibrate if you put your hand on them)

Tried to test accessory compressor to inflate spare tire - nothing happens (was in park with engine running)

I believe I do need a compete compressor unit can anyone confirm ?

Does anybody know of a direct replacement made by anybody other than GM since this would seem like a good AM product to offer