AM filter for FT-840

I just ordered a YF-112A from an Ebay seller. I've been putting it off for years, because they were fairly expensive and I had other radios I could use for SWL; but then I discovered that these filters had been discontinued and most places seem to no longer have them.
The FT-840 is a wonderful, basic radio with very good performance, but it falls very short in the SWL department because the default filter in the AM position is the factory-supplied 3 KHz SSB filter. It's a decent filter, but it is too narrow for AM; yielding only communications-quality audio. With the optional 6KHz plug-in crystal filter, OTOH, it sounds very good. You can still select the SSB filter in the AM position by simply pressing the AM/N button, if necessary due to crowded band conditions.
Anyone who has one of these great little radios and who has not yet added the AM filter, I recommend you look around for one now. Aftermarket CW filters are on the market, but not so AM filters; and when they're gone you will have to either make your own or pay big bucks for a custom-built filter, if you ever decide you need one. The radio is just to good not to use it for SWL, and if you're not taking advantage of it, you are missing out on a whole new dimension to your rig.