Barrichello, Kanaan, Tracy join entries for final testing sessions.
Rum Bum, Compass360 look to pad championship leads in the Continental Tire Sports Car Challenge.
Reigning Indy 500 winner competing for victory in second major event at IMS.
Alex Job Racing, Magnus Racing, TRG and Brumos are among the Porsche 911 GT3 customer teams. Seven of the 10 Porsche factory drivers are in the field, along with 10 previous winners.
Surprises continue to arrive in the news on Rubens Barrichello as he now plans to contest the GRANDAM 24 hour season opener.
It was the third consecutive DP pole this season for Jordan Taylor, 22, who will share the car in the race Friday with veteran Max Angelelli.
Juan Pablo Montoya fastest in opening Sprint Cup practice.