What was found
AIRCRAFT WAS GROUNDED: FLIGHT RETURNED TO DFW ON ACCOUNT OF LEFT CONSTANT SPEED DRIVE OVERHEAT INDICATION. AN EMERGENCY WAS DECLARED. MAINTENANCE FOUND VISIBLE DAMAGE TO THE CSD UPON INSPECTION. REMOVED AND REPLACED LH ENG CSD TRANSMISSION, GENERATOR, AND CSD OIL COOLER IAW AMM 24-00-01, 24-20-01, AND 24-10-03 RESPECTIVELY. FLUSHED OIL LINES, OPS AND LEAK CHECKS GOOD.