I have owned my '71 Dart GT since August 18th of 2003. Factory equipment on my car included 318, 2-bbl, A904 auto (console shifter with bucket seats), A/C, PS (Federal), Rimblow steering wheel, manual drums (front & rear), 3.23:1 sure-grip 8 3/4" rear-end.
When I first acquired my car I did some research with Chrysler Historical (an employee perk). The gentleman I spoke with told me there was a fire that destroyed many of the records they had. However he told me ~1.3% of the 96,*** production for 1971 were GT cars. Unfortunately, he had no recollection/information to differentiate between slant 6 vs. V-8 cars.
Every '71 GT will have the A65 on the fender tag, but I'm not sure every GT was a bucket seat console car. I've seen one other '71 GT, at the 2005 Mopar Nationals, that was a column shift with bucket seats but no console. Also, my car does not have "Custom" on the glove box door (or anywhere else). The only badging it has is Dart GT on the rockers and DODGE on the trunk lid.
I have made some changes to my car. I have added an Edelbrock LD4B intake & 1406 4-bbl carburetor with Lokar throttle and "kickdown" cables, MP electronic ignition, MP viscous fan, dual exhaust (factory manifolds with FlowMaster 40s using 2 1/4" pipes), SSBC front disc brakes, AutoMeter Z-Series gauges (tach, oil pressure, water temperature & volt meter), '70 Rallye wheels (14 X 5 1/2" small bolt pattern), functional '70 twin hood scoops (4" holes and seals (from Detroit Muscle Technologies), V21 style paint treatment (hood, scoops and cowl using gloss black), a '69 Charger flip-top gas cap, 2012 Jeep Wrangler headlamps (on relays) and MAD Electrical style wiring modifications.