As described in post № 80 in this thread, the Sylvania type does not work in lamps with fresnel lens optics, only the soon-to-be-NLA Philips items linked work in those lamps, and there are a lot of those brake lamps on old cars like ours.
But there are also a lot of non-fresnel brake lamps on old cars (it varies by model and year). If your car has non-fresnel lights, then it's a "try both and see" deal, as per the link in post #80.
