The N6b's were rebuilt from 4 wheel wood under frame classes in Lines West shops, starting around 1914. The cupola placement varied because some rebuilds extended the body on only one end (leaving the cupola near the other end), whereas others extended both ends, leaving the cupola in the middle. A main spotting feature of the N6b was it's narrower cupola with sloping sides (tunnel clearance for Panhandle division's 10 tunnels on Pittsburgh to Columbus route). Some N6b's were transferred to PRR divisions east of Pittsburgh, where they were photographed as late as 1964.

Requires Trucks and Z-Scale couplers.