In most searches for rear wheel well liners, the results will point to a discussion on part # 19166677. If you search on GMPartsDirect.com you'll also get this number when searching for "wheel well liner" (with the only caveat that it won't fit dually trucks, no mention of not fitting anything above a 1500). In most internet searches there's a good chance you'll end up with this part number as well. #19166677 shows up everywhere.
Unfortunately, part # 19166677 is NOT the correct wheel house liner for a 2500HD truck. There is actually a different part #, 22738993 for the 2500 series trucks (and I believe yet another part number for 3500's). The reason for this is that the 1500 series liner will not clear the 2500's suspension. The 3500 liner also has an additional cut out for the heavy duty bumper mount installed on the outside face of the frame rail on those trucks.
As I said, this has been discussed elsewhere on several occasions, but it doesn't pop up readily in a casual search for the liners so I thought I'd sorta bump it by starting a new thread.
Edited by Mac2500HD, 12 August 2011 - 08:36 PM.