Gary - before you start to throw parts at it, have you been able to definitely to pinpoint the noise as coming from wiper bushing?. If not, can you get someone (or you) to lay on their back with their legs over the seat and head as best as possible under the dash while The car is being driven on your bumpy road to determine what/where the noise is coming from? If it is the bushings I think Schumacher has them with their wiper pivot kit. Or could the wiper motor nuts that secure the motor to the bracket be loose. Try troubleshooting it and let us know.