As you probably know, the exterior color code should follow the 65A which is the body style which is a hardtop. There should be a letter immediately following that such as "M" or some other letter indicating the exterior paint color.
The DSO code is the district code but should only be two numbers such as 31 (Cincinnati)
Look more closely at the 4th digit to see if it somehow got pressed out....maybe there is still a trace.

 

One other thing, that 6 consecutive numbers is not your DSO code, that's the Consecutive Unit Number. The DSO(district) code is only two numbers which follow directly after the Date code.

 

You have a "special order" paint color that was not listed as a Mustang color. The DSO should be 75 (Phoenix) with the 0315 being the 315th special order from that DSO in that model year. I have a 1966 High Country Special that has a blank paint code and a six number DSO(510246) 51 (Denver) 0246 the 246th special order in the Denver DSO for the 1966 model year.
Because it is a 1967, if you want to know more about your car, you can buy a report from Marti Auto-Works(I am not sure if the reports list the specific color of "special order" paint though, it might only tell you that your car had "special order" paint).

 

Great information Lee. I never realized there were factory special order paints for vintage Mustangs. Now I do...

 

If you decide to investigate the paint color on your own without buying a report, a few good areas to search for original color is under the dash pad, under the roof rail seal moldings and under the deck or hood hinges. I have a 66 special order paint, and these areas were untouched when I checked them out on mine.

 

My 67 Coupe doesnt have an axle code stamped on it. Anyone know why?

Travis

 

Your axle code may be behind the rivet holding the dataplate.

 

I'll second the information about it being a special order. A buddy of mine sent a 1 of 100 car to the recycler last year. I got the doors off of it later and decoded the tag to find this information out. I kind of wish I never knew now.

Kevin Marti at Marti Auto Works(http://www.martiautoworks.com) can probably tell you more about it.