General Motors is conducting a safety recall of about 5,000 heavy-duty Chevrolet Express and GMC Savana passenger and cargo vans and halting production and sale of the trucks until a fix for a suspected faulty alternator can be determined. Retail and fleet customers who purchased these vans, which were built in February and March this year, are being urged to stop driving the vans, park them outside away from buildings and other vehicles and, if possible, disconnect both battery cables.