I wouldn't rule out the Greenbrier train either. Remember, they have already acquired GE B39-8s for their initial operations. It also may not be a stretch to do freight-style brakes on the rolling stock, similar to what Amtrak does on its cars assigned to Auto Train service.

Are there any railfans out in the Philadelphia area who could do a recon? Pottstown, where the cars are undergoing rehab, and New Hope, where the NH&I shops are doing the locomotives, are just a short drive apart, and someone could probably find out some info easily.