From:Mutt e-mail:pigstye13-A-aol.com
Subject:RE: RE: RE: Hummer Date:Sat Sep 12 21:28:52 2015
Response to:20756
Dave, we had a discussion here on the site about the frames.
We sent in pics of a bunch of frame numbers. I could have
swore that they were added to the Frame Section at one time
or another.

Harley started stamping the frames in 1952. The stamp is a
letter and a single digit number, pretty large font, maybe
1/4" or so, lower left side of neck casting. A2 (Jan 52 and
so on.) Started stamping the Panhead frames that year also.
Spine of frame, right side, to the rear of the rear tank
mount tab.

Belly numbers were like 3 digits followed by 4 or sometimes 5
digits. The first 3 (5/64" if I remember right) were the
series and the year, the larger 1/8" numbers following were
sequencial numbers stamped on each case half to show they
were machined together as a pair.

Mutt

----- ORIGINAL MESSAGE FOLLOWS -----
Duane,

You are right about the numbers. More information about the
various numbers found on a Harley can be found here:
http://www.harleykmodel.com/technical/numbers/index.html

Some of the info there is K/Sportster specific. I'm not sure
what the format of the "belly numbers" on a Hummer-series
bike looks like. I'm not sure if the Hummers even had frame
date codes. Maybe someone with a bunch of engines and frames
in their shop can answer this.