Stock. I relocated the coolant tank to where the intake hose went into the fender and drilled right through the fender where the coolant tank was. I still need to make a cap for the part of the air cleaner near where the intake hose connected to close off where the exhaust manifold pre-heat hose hooked up to. The air cleaner itself is sealed with RTV on the carb gasket and inside the rim of the cover. For both of those I let the RTV partially set first before putting on. Also have a thick rubber gasket about the diameter of a quarter (which in a former life was a faucet gasket) used to seal the retaining nut which holds the cover on.

Are you thinking about a supplementary air cleaner? If so, I haven't considered that but I'd like to hear your idea if you are. Better PM me the response or answer in that other thread tonight about the snorkel post in the Toyota Forum so we can quit this hijack.