I have a 1971 Dart GT (A65 required on fender tag). It is a 318, 2-bbl, bucket seats, console shifted A904, A/C, PS, RimBlo steering wheel, 8 3/4" 3.23:1 sure-grip, 10" drums all the way around. Also, the "DART GT" emblems on the lower rockers.
From the conversations I've had with Chrysler Historical there was a fire that destroyed many of their records. The gentleman I spoke with, said his best guess was about 1255 for 1971 (~1.3% of the ~96,000 cars built).
Does the vehicle you're speaking of have the fender tag or build sheet?
There was a member here, Bruce, who had a website dedicated to '70 & '71 Dart GTs. Unfortunately Bruce passed away and I believe the website is no longer active.