Brakes

Ok so i went to buy new shoes and drums for my car. I have a 2000 four door with nothing special besides tc, and air. They told be there were two different sizes for drums and wheel cylinders.

Drums were like
7.87 or i think 8

Cylinders
bore is either 7/8 or 11/16

How would i be able to tell without take apart the rear

Does it not say in you're manual? Or do you not have a manual? Haynes manual may say as well.

i have the typical used car. always comes without a manual