Where to find used parts for E series diesel?

Specifically I'm looking for the cover to the airfilter box/intake for my 1997 E450 7.3 diesel cut out van. My cover has a large crack all the way across the lip, just behind where the clips pull it tight to the airfilter housing. It's currently mended with a heavy bead of JB weld, but I'm looking for something a little more durable. I checked with the dealer and the part is not available without buying the entire inake assembly for around $350 - no thanks. I would imagine there are some salvage businesses that would have all kinds of parts for these but I can't seem to find any through my own searches. Any ideas?

Thanks,
Bob