[Arathke]

Sold new to my aunt from Rosen Novak Auto in Denver, CO.
It was repainted in the 70s and matched as close as they could at the time, as well as changed to metallic. Original paint can still be found.
No special badges even in pictures before the re-paint, not a High Country.
The closest I have gotten to finding the true color is from MustangAttitude, however, they describe convertibles
"Emerald Green (MX7041537) was the same paint as 1967 Timberline Green and used on several 1967 Saint Patrick's Day parade convertibles. Little is known about this special order car. They were probably built in the San Jose plant for the Denver area under a special order with a blank paint code, and probably without a special fender commemorative badge."
Is this most likely what color the mustang is or does anyone have a different idea or lead? Thank You!!

 

[Woodchuck]

Could be somebody liked the Ski Country Special's "Loveland Green" and said "Let's get a fastback in that color!".

 

[Sunlit68]

Great looking car!

 

[63BGT66]

No paint code and complete DSO indicates a special order. I had the same issue and found original paint on the inside of the folding seat back.

 

[1ofAMillion+]

Greens are tough to discern from pictures. Even finding hidden original paint can be misleading.
Being made that far into the model year it could be a Next Year color so look at '68s as well. Possibly it was a production color offered on Lincolns or TBirds before it was a standard option on the lesser cars. Look at a bunch of those cars for light and shadow variances to help eyeballing it.