This is indeed a rare item, a new camshaft gear for the M-136 flat head 180 motor.

This is made by SWAG, an OEM supplier to Mercedes.

This will fit the M-136.925 motor used in the 180 model 120.010, see listing below.

This is the timing chain gear on the camshaft.

The Mercedes part number is 181-052-01-01, and I am not sure if it is available any longer from Mercedes.

This new camshaft sprocket will fit the following years and models Mercedes:

180 - 120.010 - M136.925 motor - 07/1953 through 06/1957 production.

All applications are accurate to the best of my knowledge, however I advise double checking with your dealer for application to your vehicle, or email me with your VIN # for clarification. I can not be responsible for inaccurate or missing application data, however I will take an item back if the error is mine.