Originally Posted by Jordan Y.

Oh, and GM uses the strangest selection of bolts and nuts. With my car, I use a 10, 12, 14 or 17mm socket for 95 percent of the bolts on the car. The other small minority are very large metric sizes like 19, 21, or 24, and the only standard bolts on the car are a handful in the seatbelt system, which was made in America.

On the firebird, there are 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 mm bolts/nuts, just to name the ones I've run into today, and also a wide range of standard bolts, 1/2", 5/8", 3/4", 11/16", and on and on and on. Sometimes, they use a metric size for a bolt, and a standard size for the nut that goes on that bolt! There's also hex head bolts, torx bolts, and other oddball fasteners in places that just don't make any sense.