just had my clutch packs replaced and "1 side gear and pinion kit" replaced in the truck today. i think the gear and pinion kit had something to do with a "spider" or something inside the differntial. driving home from buffalo to rochester tonight, i drove all the way home with no problems, and then coming up to a light in my town, started to hear a noise that sounds like a flat spot on the rear tires, making a thud thud thud thud noise. it only happens when i'm slowing down, and is most loudly heard at deceleration from 35 down to 20 MPH. then when slowing at speeds under 20 it is hardly heard.

is something wrong with my tires? or is this common to happen after such a service? i will call the place in buffalo to ask tomarrow morning, just thought i'd look for some ideas tonight. Thanks for any suggestions and happy new years!!!!
John