From airrace.com is the following for the 1968 Cleveland National Air Races:
A new class bowed in, for stock North American AT-6s and SNJs and Harvard advanced trainers. A demonstration race at Reno in 1967 proved popular, and so they became a part of the program. Nineteen of these warbirds arrived, though only 12 could fit into the preliminary heat races. Top qualifier was Howard Keefe at 179.700 mph, second was Whit Halfhill at 179.104 mph. In the Finals, Hendrik Otzen won at 181.322 mph, Richard Sykes was second at 181.246 mph, and Phil Livingston was third at 180.980 mph. All their races were close and loud.
http://www.airrace.com/ConciseHist.htmHere are Reno results for Hendrik Otzen the same year:
Race: T-6 Qualifying Date: 1968-09-19 Course: lap, 3.00 mi
Pilot: Otzen, Hendrik Aircraft: Condor - Race 1 Type: SNJ-5
Time: 01:00.6 Speed: 178.2200 Place: 7
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Race: T-6 Heat 1 Date: 1968-09-20 Course: lap, 18.00 mi
Pilot: Otzen, Hendrik Aircraft: Condor - Race 1 Type: SNJ-5
Time: 05:55.8 Speed: 182.1300 Place: 1
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Race: T-6 Championship Date: 1968-09-22 Course: lap, 24.00 mi
Pilot: Otzen, Hendrik Aircraft: Condor - Race 1 Type: SNJ-5
Time: 07:56.5 Speed: 181.3200 Place: 1
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http://airrace.org/race_results/results.php