If you want to drive it often I would jack it up and remove the rear wheels. Then have a friend start it up and put it in drive and get it up to where it should be vibrating. Watch the drums and see if everything runs out smoothly. Also it is possible a balancing weight came off the drum. A good machine shop should be able to check balance on the drums. Hope this helps.
Bad idea running the speed up to 55 MPH with nothing holding the drum on the car.
I’ve done this more than once. Just use 3 of the lug nuts, backwards, to hold the drums in place.
I'm a hobbyist. Not a professional. Don't be hatin'!
