Four hours to go:

Prototype: now Mazda #77, Acura #7, Cadillac #10

GTLM: now Porsche #912 (13th overall), Corvette #4, Ford #67 (Corvette #3 now 4th in class)

GTD: now Mercedes #33 (23rd overall), Acura #86, Lamborghini #48

32 out of 37 of the original cars are still running. The #6 Acura is back on the track, 134 laps down.