What was found
DURING CRUISE, LEFT ADC BECAME INOPERATIVE. FOLLOWED QRH, CA SWITCHED TO ADC ALT REMAINDER OF FLIGHT OK. AIRCRAFT DIVERTED TO MIA DUE TO RVSM RESTRICTIONS AND THERE WAS NOT ENOUGH FUEL TO GET TO CVG AT THE LOWER ALTITUDE. LEFT AIR DATA COMPUTER REPLACED IAW AMM 34-12-01/401. ADC TEST ACCOMPLISHED NO FAULT, MCDP TEST 30 ACCOMPLISHED WITH NO FAULT, SYSTEM OK FOR SERVICE. AIRCRAFT REMAINS NO ETOPS.