I think Evan (coilover) made some of these a few years ago...3 years, maybe? You might send him a PM. If you need to shim the front part of the cab up higher (it will commonly sit down on the frame and avoiding that by even 1.5 or 2mm will eliminate a decent amount of noise coming from the frame straight into the cab) get some of the sheet pvc material used for shower pan liner and cut yourself some washers from that. It is thin enough you can use a couple or three layers. That noise is the same principle as two cans and a string for a "telephone."

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end