New Rear drums...vibration issues

[Dubv]

I recently replaced the rear drums on my '84 Eagle wagon.  Also just recently got new shoes installed as well along with some other work I needed done by an old AMC dealer tech. 
I purchased the drums from NAPA...they only had one quality level available for the Eagle.  Installed the drums, and noticed that after a bit of driving that there was a vibration on braking...went and felt the rear lugs and they were hot.  So I eased off on the adjusters, and have driven the car some more...still have one side that is getting hot after 20 or so minutes of driving and experiencing vibration on braking.  I've got the shoes adjusted about as far "in" as they will go.  The drum seems very "loose" on the lugs...actually seems to want to slip off until the wheel is bolted up tight to it.  I have gone through multiple attempts to adjust the brake shoes on that side...but each time, the same problem arises.
So the question is..has anyone had any issues with NAPA drums not fitting correctly, or any other thoughts on what might be wrong?  The brake cylinder isn't seized, so thats not the issue.  I'm also getting some vibration about 55 mph without braking as a seemingly seperate issue, but it could be related.  I had assumed that was just a wheel balance issue in the rear as well as the steering doesn't shake but I can feel it in the seat and the driveline coming from the rear.  Any thoughts much appreciated!

[AMC of Houston]

This is way out in left field; but since its thee right side, possible the dreaded Eagle fractured axle??    With everything bolted up and the wheel off the ground, see if you can get any little bit of wobble at all by yanking back and forth on the tire.   

Only other thing I could think of is if the backing plate nubs that the shoes ride on are worn (a groove that the shoe sticks in so it doesn't return to its "at rest" position).   I had some weird rear brake issues on my '85 due to that - welded up the grooves and smoothed them back to "as-new", and my issues went away.

[Dubv]

I had tried shaking the wheel with it jacked up...seeing if something was loose, but it all seemed tight.  I'll check out the pegs they ride on...that would be a weird/interesting problem.

[mudkicker715]

No vibration before the new brakes?

[DAVE]

the original drums were held on by a screw if the screw was put back in then the new drum put on it might not be riding flush and true causing vibration

[Dubv]

Just to give everyone an update.  The vibration issue is still there.  I've had it at my AMC mechanic's place....one issue seemed to be that one of the new drums was not balanced.  He was able to improve the vibration by balancing the drum and the wheel together on a wheel balancing machine...but even with all new shoes and drums, the right rear continues to heat up after being driven for awhile as if something is rubbing.  Using a thermometer it is 15-25 degrees warmer than the other side even after a drive with minimal brake use.  The bearings and seals have both now been replaced on that side as well...but it did not change the heat issue.  He said the axle looked fine when he pulled it out to replace the bearing and seals as well.
We are both pretty stumped...and although the drum may have been part of the problem, the heat still being there even when the drums are switched side to side seems to point to some other problem.  Any other ideas?

[AMC of Houston]

Have you replaced the rear metal brake lines yet??    On every one of my old AMC's I've done the rear brakes on, the metal lines were all cruddy/rusty inside -- so much crud that there could have easily been some piece of crud acting as a "one-way valve" in the line (keeping pressure on the shoes at all times).   I always just made new lines just in case.

[AMC1]

I'm joining this conversation kind of late but here goes. You mentioned the problem/solution. That drum should not be loose enough to want to slide off until the wheel is bolted to it. It should be a tight fit even if no shoes/linings were installed. I don't know if Napa has a core charge on those parts but I always keep my old parts to compare to replacements before returning for a refund on the core charge. I would like you to compare the various inside & outside diameters on that drum - even the 5 bolt hole pattern ID's.