The rod is a 31380C not 3180C.
There is a Tecumseh engine group and I asked them about this rod. Below is the reply. Given the part number change and no cross the chances are pretty slim of a match.
Response:
I don't have any spec's on the rods. The only thing I know is that in the suppression list they don't go back to a common part number so something is different. Sorry I can't be of more help but I just don't have that kind of information.
The piston's are the same, the stroke is the same, the diameter of the crank pin is the same so maybe the width of the rod is different at the crank pin????? I don't know.
