Serial number question

[Mike Dix]

I have a project 29 JD . The engine case is stamped 29 JC . What does the “C” stand for ? I’ve been told commercial ? Maybe the stamper was moonlighting at Miller Brewing Co.

[MMasa]

You were told correct information. C = commercial
Mark have been a package truck, etc.
A JC would be a 61", low compression, generator equipped, and probably with a large rear wheel sprocket.
Is it a JC or a JDC? (61" vs 74")
Mark

[Mike Dix]

It is a JC . So I have a 61”. I’ll check the rear sprocket also. I’ve done many projects and they have all been assembled when I bought them so I could take a bunch of pictures through the disassembly. This one is in box’s and I’m finding I have a challenge on my hands . Loving every minute of it! Thanks

[MMasa]

Well, the VIN indicates that it's a 61" but all you have to do on 1924 and up cases is use 74" flywheels, cylinders, and a few other small bits and it's a 74"
Mark

[aumick10]

Is there a difference between the 61" and 74" rod lengths?

[MMasa]

Not from 24 or 25 up. I'd have to look in my notes to verify which year.
There were 74" specific rods for early 74's. 1921-24? non DCA motors.