The problem with air box haters is that they think they are worthless and either throw them away or "loose" important parts that are needed for their use.
I picked up almost-a-complete-set-up years ago on Ebay, for $2.00 plus shipping. Mine was the only bid. It went on a bike that came to me with a K&N monofilter.
I had to make the filter spring.
You just have to have timing...and patience.
Cheers,