Knuckle couplers for the 1/32 OpenRailway EMD SW1500

I've designed knuckle couplers that fit the 1/32 EMD SW1500 (http://www.thingiverse.com/thing:916416).
It wasn't easy as space is scarce but it works.

The hook and tang are cut in 2 so they can be printed without support (when printed with support, the result is too rough to ensure smooth operation).