From the underside of the car, with the headpipe off, thread a nut onto the stud coming out of the drivers side manifold. Then thread another one against the first. Using a wrench you can now use the first one to back the stud out of the manifold....the second nut will keep the first one from backing off. Go easy....don't try to horse it off. YOu definitely don't want to break the stud off. You ccan use some penetrating oil if necessary. Once you get the two studs out you can either replace them or grind the spacer off with a bench grinder, then reinstall.