A company called Auveco, web site " autofastenersandclips " a big supplier / source of factory hardware, Excellent catalog source for Hardware identification size, etc., and especially the unusual clips and nuts and bolts, wire loom and hose support clamps. You can use factory part numbers here also.
Another is " Clipsandfasteners.com " . You can search by make, model etc, or the factory part number. I have purchased from " clips and fasteners" off Amazon there discounted. When removing the door card, the upholstery inside , there is always a few of those white barbed pins that break or the retainer breaks, so I have bag of 25 in my clips supply box. They had the big clip nuts for the front skid plates, the K2500 has all metal plates. Some have plastic shields.
You don't have to buy from them , the point often is just being able to identify what you need to look for. And once in while the dealer actually has the part on the shelf for reasonable price.
Good luck!
