67-72 Air suspension/driveline issues- Need some help

[heymoe]

Here's the skinny,

I have a 67 SWB that has a complete mild air suspension from ART. I have almost the entire Porter catalog except for the dropmember. I am having some issues with driveshaft interference when I air up. The rear bags almost have to be completely aired down and the front has to almost as low so that the driveshaft does not contact the center crossmember. I am looking for some advice on how to trouble shoot what could be the problem. The shaft is 3.5" diameter. I had this sized to meet the horsepower the engine. Could this be a pinion angle issue? Can you shim up the transmission mount?

Any help would be greatly appreciated.
Thanks
Also I can post pics later