That's really weird...all I could find was 03-07 pockets too (PN 15903412).
I just called my buddy at the dealership...he said that the bucket and the door come as one 'part' on the 08-09s. So maybe it's not 'rusted' together...
The PN is 25980675. The diagram here shows it as one unit...
http://parts.nalleygmc.com/showAssem...emb ly=392275
I bet you could use a 03-07 bucket...I can't imaging that they changed the alignment of the screws that attach it to the pipe.
Hope that helps.