However, the best way to find your part at the best price is to get the gmc part number, sit down at the computer and search "gmc door XXXXXXXX" where "XXX" is the part number.
Also use google with a search like: 'gmc door "XXXXXXXX"' where "XXX" is the gmc part number. You might surprise yourself. Of course a junk yard or locator service tied in with a junk yard or several junk yards would be another approach.