CM871 Crankcase Breather Filter Update?

[Pramantha]

I've searched through some of the posts but not sure which part I need for the better breathing update. Quickserve says I need 4312011 or fleetguard CV50633, anyone tell me what the update unit for me is and where/if to drill holes?

Also, any advice about how to test if the air compressor is guilty of pumping excess pressure into my crankcase? The compressor does seem 'rattley' when building pressure...