I picked up this left side Knuckle case a while ago that looks a bit odd. The only stamps are on the inside '112-406'. No other stamps. Also, no reinforcement ribs. Just smooth. Could this be a later year factory replacement or what? Any ideas? I also have the matching right side case '112-404'.

 

Too hard to tell in your pick but there is a tab below those numbers. That will give you the month and year of the case side...it will be a letter and a number. The letter depicts the month; the number depicts the year.

Case looks like it has been polished; hard to say from the angle of the pic but I am thinking someone may have ground down or filled in the vin plate. So i would suggest it is not a replacement case.

And one additional note...knuck case had ribs extending out from the sprocket area to the outside edges of the case. Someone chose to grind those away as well.

If you want to see some OEM cases go to www.vintageamericanmotorcycles.com It is a free site. Scroll down to vin numbers and you will see some cases with good (and a few with bad) numbers as well as the ribs that extend out.

 

Thanks for that info. The case is polished and the tag is 'A7', so that would make it Jan 1947? Any guess as to why someone would grind down all the ribs? I looked very closely and I don't see any sign of grind marks anywhere.