Check the listing for details. Vintage Minature Model Airplane Engine Crankshaft Possibly For Herikimer OK CO-2. Condition: Used. Listed at 19.99 USD. FREE Shipping Lower 48 States !! Vintage Minature Model Airplane Engine Crankshaft for Free Flight / Control Line Engines possibly fits a Herkimer OK CO-2 engine ??? This crankshaft arrived in a box with several other miscellaneous parts as well as a Herkimer OK CO-2 engine currently listed seperately at this time so it DOES NOT GO WITH THIS CRANKSHAFT PICTURED. What I noticed is the end or the crankshaft is threaded to accept a screw or small threaded section. The 2 machined areas shown on the crankshaft look like they might line up with the 2 holes on the CO-2 engine block I have shown for comparison only. Crankshaft Measurements are shown in the pictures, CO-2 Engine shown in the last 3 photos is not included here & only shown for comparison pictures crankshaft is sold as unknown application.