[SS Tim]

Its great to see old threads do some current good.
If the carrier is factory stock it will be listed as P13 S/M WHEEL CARRIER on the SPID. However many were sold as GM accessories and many aftermarket versions exist.

It was located, by the factory, on the left bedside forward of the wheelhouse. The mounting specifics are in the assembly manual.
Off the top of my head there is a smaller than standard floor bolt hole that locates the carrier it and two other holes are drilled to fit upon bed assembly. If I get a chance I will confirm/expand later. It has two or three different distances SWB, LWB and I believe Longhorn specifc. Really need to dig through my assembly manual. But basically the tire tucks to the wheelhouse.