E-R Models Sharks are HO scale. They share the same drive as the E-R Models FP-7. They have Roco trucks, A very nice can motor and come with a DCC ready plug.

I think Roco built the Model Power Sharks and E-R Models used the Roco design in their Sharks. They just  upgraded the motor and added a DCC ready circuit board. 

http://www.tcsdcc.com/decoderpics/erm.html

E-R Models makes (or made) a very good running Sharknose. There is a bunch available on Ebay right now.