I just posted a bunch of measurements for the side mount carrier a few days ago. It's not very complicated. I'll bet if you didn't really HAVE to have OEM you could pay any backyard welder to fab one up in about an hour start to finish. It's just angle iron and rods with a plate on the front. See 'em here.
http://6066gmcclub.com/forum/showthr...9405#post49405