KZ400 Airbox question

Hey guys. Just picked up a 79 KZ400. It has an airbox that I am trying to find a filter for, but it doesn't seem to be terribly common. Most of the air filters I am finding online and sources like ebay for this year sit inside the airbox and are cylindrical, like these:

www.bikebandit.com/houseofmotorcycles/19...b/o/m150611#sch81504

However the one I have seems to be the style that bolts onto the back, kind of like the kz305 airbox filter style. Here's some pictures:





It seems to fit pretty nicely in there and bolts into the frame so I think it belongs there. Can anyone point me towards a source for an air filter?

Thanks

You have a LTD with most of the stock air box. The piece you are missing fastens to the back
covering those square holes. I recently saw a new old stock piece go for $80 on eBay. A local
rider has the same setup. He has stock jetting and foam covering those holes. At first he had
to much and caused a rich condition. He cut the foam to half the thickness and solved the the
problem, still running the stock jetting.

.

Alright thanks man I'll give that a shot

Here's the parts diagram for your air cleaner so you can see what's missing. You may be able to find the missing parts on eBay. Ed