My PRR B1 has reproduced itself into a PRR Class BB1. When PRR bought the first batch of the units, they came in BB1 configuration. The units were semi-permanently joined together. Only later on in life did PRR separated them into single B1 units and ordered further units as B1.
PRR Class BB1 by dr_spock_888, on Flickr
As a BB1 model, there is room to add Power Functions. An XL-motor can replace the M-motor if more power is needed.
I had to add tires to the drive wheels to give it more traction around curves. I find the 0-6-0 wheel configration fascinating in these electrics.
YouTube video:
More pics on my BrickShelf: http://www.brickshel...ry.cgi?f=539207