SUMMARY: GM ADMITS THERE HAS BEEN A PROBLEM AND HAS DESIGNED A MODIFICATIONKIT INTENDED TO PREVENT PULLEY BOLT FAILURES BY KEEPING THE PULLEY INPROPER ALIGNMENT WITH THE CRANKSHAFT AND THEREBY REDUCING THE BENDINGSTRESS ON THE BOLT. GM DOES NOT BELIEVE THE PROBLEM IS SAFETY RELATEDAND WILL CONDUCT A SERVICE CAMPAIGN.ANALYSIS:THE HIGHEST FAILURE RATES HAVE OCCURRED ON VEHICLES EQUIPPEDWITH AC AND PS WHICH USE A TRIPLE SHEAVE PULLEY. THE MODIFICATION KITSHOULD REDUCE THE FAILURE RATE ON THESE VEHICLES.STATUS: GM LAUNCHED A SERVICE CAMPAIGN IN FEBRUARY 1987 APPLICABLE TO185,000 T BODY VEHICLES EQUIPPED WITH TRIPLE PULLEYS. (PRODUCT CAMPAIGN84C27)EA CLOSED 9/4/87===