I know who you were talking with. I mentioned this to him last year. The 1924-25 Model C/D manual clearly states a right and left connecting rod with different numbers. I don’t know what the difference is. In 1926 the manual states the same part number implying that the rods are interchangeable. I believe the later rods have a different part number than the earlier ones, but I’m going from memory which is often unreliable.
Wayne
Upper Canada Chapter
uccaomci.com