I don't know of any "chart" that gives the sizes by model and year but Gibson uses both sizes. My suggestion is that you get yourself a quarter inch drive socket set which is handy to have anyway. You don't need the highest quality stuff. Stop by a local auto parts store or hardware or Sears and pick up a set. A set will also have a short extension which I find makes the fit easier. (Under 20 bucks, often about 12-15)

Spaw