Technical Service Bulletin 15216 — 2015 CHEVROLET SILVERADO 3500

15216 - CUSTOMER SATISFACTION PROGRAM. CERTAIN 2015 MODEL YEAR CADILLAC ESCALADE AND ESCALADE ESV; CHEVROLET SILVERADO LD CREW AND DOUBLE CAB; AND GMC SIERRA LD CREW, SIERRA LD CREW DOUBLE CAB, YUKON, AND YUKON XL MODEL VEHICLES THAT ARE EQUIPPED WITH A 6.2L ENGINE (RPO L86) AND 8-SPEED AUTOMATIC TRANSMISSION (RPO M5U) MAY HAVE A CONDITION IN WHICH THE U-JOINT RETAINER BOLTS LOSE INDEX. IF THIS CONDITION OCCURS, THE CUSTOMER MAY HEAR OR FEEL A “CLUNKING” NOISE WHEN CHANGING SPEED. IF THIS CONDITION IS NOT CORRECTED, REDUCED CLAMP LOAD MAY CAUSE THE PROPSHAFT TO MOVE RELATIVE TO THE AXLE YOKE AND THE CUSTOMER MAY FEEL A VIBRATION. IF ONE OR MORE BOLTS BACK OUT COMPLETELY, THE PROPSHAFT MAY SEPARATE FROM THE AXLE RESULTING IN A LOSS OF DRIVE AND POTENTIAL DAMAGE TO THE UNDERSIDE OF THE VEHICLE. DEALERS ARE TO REPLACE TWO U-JOINT RETAINERS AND FOUR U-JOINT RETAINER BOLTS WITH NEW BOLTS THAT INCLUDE AN ADHESIVE PATCH.