Two problems related to transmission failure have been reported for the 1999 GMC Safari. The most recently reported issues are listed below.
1999 GMC Safari transmission failure. See gm TSB #00-07-30-002 dated 11/2000. 1st-2nd late shift, reverse, 2nd, & 4th gear caused immediate failure. All required transmission service performed by dealer on this vehicle. Root cause is the known sun gear shell failure in the gm 4l60e automatic transmission. Vehicle has 70,511 miles. Filed GMC customer complaint #1-366073225.
I own a 1999 GMC Safari that had its transmission fail at less than 50,000 miles. It failed before its first scheduled maintenance. I contacted the dealer and was told I was out of the 3/36 warranty period so I was out of luck.