Here is the number i got for the dealer about this,,,,,,TBS 05-05-00
Goes on to say about the axle shaft drum pilots being wrong size or non-existent.
Subject; Rear brake clunk or thump when brakes are applied
Date; May 26 , 2000
A clump or thump may be heard coming from the rear of the vehicle when the brakes are applied on some vehicles with 8 .25 inch rear axle. This may be caused by an axle shaft,which does not have a correct size brake drum pilot flange.
Ther must be 2 seperate pilot diameters on this area. The outboard diameter for the wheel ( 2.812 - 2.808 inches ) and the slightly larger inner diameter to support thr brake drum ( 2.832 - 2.826 ) inches. The brake drum pilot may be missing or mat not be deep enough to support the drum.
If the drum pilot does not adequetly support thr drum,some movement of the drum may occur when the brakes are applied causing this noise. if the condition is present ,perform the repair procedure.
In other words install new axle shafts.
think i will try a shim of some sort ?????