Two problems related to driveshaft have been reported for the 1999 GMC Safari. The most recently reported issues are listed below.
While driving over 50 mph vehicle vibrated. Consumer was in touch with the dealer and manufacturer, but the problem still existed. Consumer stated that the driveshaft was the problem, yet they won't do anything about it.
The drive shaft splines needs constant lubrication. There is also leaking from the transmission extension housing.