I did some searching, didn't find much information on a Dearborn car with a similar build date.
My car is date code 29K unit number 3399XX. It has been in the family since new. I tried to detail the bottom when I was a kid, back around 1980. Being a kid, and not knowing anything about restoration, I didn't document what I found at the time. I remember the car being black underneath with very little white overspray (car is wimbledon white). being that long ago, who knows if my memory is even close...
Now I am redoing the car and would like to make it as correct as I can. Anyone have any similar build date cars from Dearborn, with information to share?
So far I've studied the VA Mustang blog on their "early K" convertible, but I think that was produced earlier.