K = Kelsey Hayes (manufacturer of the rim for GM-Chevrolet)
1 = plant at Romulus, Michigan (for GM-Chevrolet)
9 = 1969 (Year of Manufacture)
Now, as I am searching around for info, in prior years of 1969...
KH rims being manufactured for Chevrolet, in my image above,
the earlier rims only used a single J after the rim stamping of the size and width.
Example : 14 X 5 J
Does the single J denote anything towards how the rim fits the brake system?
Where as, in 1969 JJ stamping, does the JJ represent anything towards brake system fitment?
What is curious to me is if the early 1969 Z28 AD rims were stamped with JJ or J ?
I would assume the the YH rims were having the JJ satmping.
In my image above, you will notice the letter A below the 14 of the 14X7 JJ stampings.
I am going to guess that this denotes the month that it was made.
This image is from one of my YJ rims in a set from January 1969.
To add, there is also a letter in the wheel center that seems to denote the month of manufacture, K-1-9 A.
On this particular rim, the A is stamped just under the GM stamp on the wheel center.
I am going to assume that the outer band was manufatured in Jaunary, 1969 by looking at this.
I am going to assume that the wheel center was manufatured in Jaunary, 1969 as well.
I decided to go and look at some of my other rims.
K-1-8 trhru K-1-9 issue.
Some of the K-1-8 rims have the Letter code in the wheel center on another of one of the 5 landings of the rim where it it can be stamped.
One set, stamped for October, 1968 denotes a 10-X date.
These rims show a K-1-8 with a Letter J.
Counting out the months, J lands on the month of October.