OM 636 Crankshaft Part Number

[James Allen]

In my efforts to replace the crankshaft in my 170V engine. I found a crankshaft from an OM 636 engine. I checked the parts reference book and found that the OM 636 crankshaft will fit into the 136 gas engine as the stroke is 100mm and the crankshafts are the same. Okay, so I went forward. With the purchase, I received the crankshaft, which was in excellent condition. I will have to grind the crankshaft to match my new bearings from the previous crankshaft. Upon receipt of the crankshaft, I noticed it did not have a clutch pilot bearing, and the counterweights were much heavier than the original pre-war crankshaft. Likely, this crankshaft came from an industrial constant speed application.

The part number on the crankshaft is R681 031 0001. What does the part number reference toward?

The lack of pilot bearing is not a problem, as I can machine this dimension into the crankshaft. Some extra weight associated with the more giant counterweights can be removed, rebalancing the crankshaft.
Has anyone had an experience with a similar conversion of a 636-family crankshaft to fit a gas-powered engine?

This entire job is because my original crankshaft was reground out of stroke, thus not allowing the pistons to reach the top of the cylinders. The connecting rod bearing lengths and piston pin heights are correct.
Thoughts and ideas, please.
Jim