One problem related to rear seat belt buckle has been reported for the 1999 Ford Taurus. The most recently reported issues are listed below.
1999 Ford Taurus rear center seat lap/shoulder belt assembly. Child was taking seat belt off and the attachment fell apart. The latch plate completely fell apart and the belt is not usable. Luckily I was not in a crash or this belt would have failed allowing my child to be injured.