A HEMTT cab would work for the build, but you can't beat the brand new Mk48 cabs! They make it feel and smell like a brand new truck! I got mine off of Ebay....Barstow sold like fifty of them not to long ago, so there are several available. Some members here on SS also mentioned that they had some.Well I know where there's a 939 series rolling chassis. It doesn't have an engine/trans though. I also see a few possibilities coming up for auction that might be a better candidate (actual 931's A2's exactly). Where did you come up with your cab? Would only the PLS cab work or would a HEMTT work as well? (I know they're different, but I'm wondering about the steering and cab tunnel)
The M931A2 would be a good choice I think....great fuel milage to!