Few owners of these years of Chevy/GMC trucks have any idea that a hidden adjustment door plate is built behind the actual door striker plate. Unless you read the owner’s manual that was in the glove box when the truck was new it is unknown.
Check the attached photos: The back side of the striker plate has about 13 horizontal ridges separated from each other by approx... .05” inches each. These exact ridges are also on the door post plate. Thus, this striker can also be adjusted (moved) in increments of .05” inches and they hold the door securely.
Why was this design created? As the two push-in rubber bumpers on the outer edge of the door (they prevent metal to metal contact) begin to shrink with age, the two striker plate screws can be slightly loosened to move the plate and then tighten the two screws. This allows the position in the door (operated by the large exterior chrome handle) to keep the correct connection with the striker plate.
This is a quick and easy way GM created to allow the striker plate to keep the door in the new position.
Unfortunately, the saying “out of sight, out of mind” can be applied here. As long as the work truck doors were closing, the owner had nothing to draw his attention that an adjustment was needed or could even be made.
