There you go. 406 hours, so i assumed it was a test bird! Low hours on all of them.
Those are the A12s, which was the CIA variant and got cancelled in preference to the SR71, a few differences:
A-12 /SR-71A
Maximum Speed Mach 3.35 at 85,000' (Estimated)/Mach 3.2 at 85,000' (Estimated)
Maximum Operational Ceiling 95,000'/85,000'
Maximum Unrefueled Range 2,500 miles/3,250 miles
Wing Span 55.6 ft. 55.6 ft.
Wing Area 1,795 sq. ft. 1,795 sq. ft.
Length 98.75 ft./103.8 ft.
Empty Weight 60,000 lbs / 67,500lbs.
Gross Takeoff Weight 120,000 lbs./ 152,000 lbs.
Sensor Payload 2,500 lbs/ 3,500 lbs.
Of the SR71s, 976 did the most flying, 2981 hours.