Where to find an air induction valve filter?

My friend owns a 1980 Nissan Datsun and we are trying to figure out where we would be able to purchase what I believe is called an air induction valve filter, at least according to a Haynes manual. I can’t find one online and no one has one at the general auto parts store. If it is, as I suspect, no longer readily available does anyone have any other solutions for a replacement?

If you have the old one for a pattern, maybe you can fabricate one by cannabilizing another filter, like the foam ones small Honda engines (5hp., etc) use. The main purpose of the filter is to protect the reed valves in the induction unit. The air goes to the exhaust manifold to promote afterburning, so any dust that gets by isn’t going to damage the engine. You might luck out and find a NOS (New Old Stock) part somewhere, but it’s unlikely. I’d just make one if it was mine.
Good luck!

Good Luck. I couldn’t find one for my wifes Datsun 510 back in 1986.

Examine the old one and make one…This is not a critical part…

The problem I had with the wifes 510 was the metal casing that housed the filter rusted out. I ended up going to a junk yard and found one there…but had to buy the whole breather assembly. The filter element wasn’t hard to make.