Lode51,
I believe there has been discussion of a paper gasket between the drum and the hub. The post may have been about the rear brakes but I am assuming the same exists in the front. I personally can't see what other function a gasket would serve other than some type of isolation between the two parts.
Squealing is a frustrating problem. I have a little of that with my front 1 Ton brakes, from tome to time. Years ago when I worked in a garage, I have seen brakes squeal for the first time after a brake job, when heat had been used to remove the drum. Also, some drums used to have springs around the outside and I was under the impression that they were there to prevent squealing.
