Recently the foam sock over my Lehman 120 air filter disintegrated, and I was sick of replacing it, which is a messy job anyway, and I suspect it was not a terrible efficient set-up as well. I thought of adapting the upper and lower plates with metal rods/nuts to compress between them a drum type paper filter, like Darrell (Baltimore Lurker) recently described, (an elegant solution I admit, and more environmentally responsible to boot), but then decided what the heck, and I went to Auto-Barn and got a large truck diesel engine pod filter I saw in their catalogue. They had one with the exact 70mm diameter mount, and it just cir-clipped straight on. I thought about trying to drill a hole in the top to plug in the tube from the rocker-cover breather vent, then decided the complexity that would introduce would outweigh the tiny wee gesture to a greener environment, and just left it disconnected. If that makes me a 'bad' man, then so be it. But boy, what a nice neat and clean solution, and the engine runs beautifully.