15843754 and 15049809 were the older numbers. I believe they were replaced by 20944322, 20922755. I put them on my LTZ. Non Z71 4x4 have the holes, but they are not threaded. The GM self tapping screws were $5 a pop a few years back (8 or 10 needed, cant remember). Some have used a M10 1.50 tap, but I spent the money on the GM screws. The plates are no heavy duty, so if you plan on any serious off-roading, look aftermarket...