There have been several imported in brass (Overland, Custom Brass, etc.) and you might be able to track one down at the East Penn meet that held every other year - 2017 next. There were quite few others beyond those both imports and some kits that were designed for 2-rail drives (Wagner or Q-Car), but none recently. But none in 3 rail.....
Q-car still listed bodies and full kits on their web site last I looked - resin bodies. But, you're on your own for a 3-rail drive
The one body shell that's still pretty readily available is the one that was imported by IMP that you can find on eBay just about once a month, if not more frequently. I still have 3-4 of those about in the project queue to restore and re-motor. These were actually imported in both 2- and 3-rail configurations. Finding one with a decent functional drive in it might prove challenging.
