What is the year and model of your Buick?
Rear drum or rear disc brakes?
I still need to know the model Buick you have. Is it a regal, century, LeSabre, skylark, park avenue?
Without knowing the exact model of your buick, I dont know which diagram to provide.
Also, the rear wheel assemblies are different between the rear drum brake assembly and the rear disc brake assembly, so I need to know which yours has
Here are exploded view diagram and diagram with all parts in place: