Absolutely. At this time, I haven't seen a single ZF on a dealer's lot other than my truck...
At three different dealers, I've had salesman come out and check out my truck because some have never seen, and one didn't even know they came with the ZF.
I haven't even seen any on ebay lately. If I find any, I'll definitely post them up.
2006 GMC 2500HD 4x4 CCSB Duramax/ZF
2004 GMC 3500 4x4 RC 11' Utility Duramax/Alli