I think you will find

I think you will find on the next line of your report after 531 SCJ's something like
"For the 1971 Mustang Mach I" The 531 SCJ number is the Total Amount of SCJ Mach I's Built which would include C codes, J Codes, 4 Speeds and Automatics. Which would mean your car has a lower production number than you think. Just as the 180 Color/Trim code optioned cars includes all Mach I's Ever produced I would imagine not many would have been SCJ Machs.
When Kevin first purchased the Data Base, (Before he started offering reports) He offered this group and opportunity to ask some questions and he would send a letter with his answers. I took this opportunity to ask some very specific questions about the 71 SCJ Mustangs that came with an automatic transmissions and have a breakdown total of all 5 models of mustang that came with a 429 SCJ and Automatic trans. Since I have a plain old Sportsroof, I asked even more specific questions as to how many SCJ Sportsroofs came optioned like mine, How many SCJ Sportsroofs came in the color/trim codes I have and How many came with 4:11 Gears.
This info is invalueable. I also purchased a Marti Report which the numbers are more general to all Sportsroofs.
A More Detailed breakdown is Included in the Elite Report or by ordering the personalized stats.
Hope this clears up the confusion