WARNING: You must be careful with this setup if you cross water deep enough to submerge the duct inlet. As it is sealed setup, it will cause water to be sucked up with the in-coming air and enter your engine and cause severe problems. This is the reason behind the rubber coupling. I would highly recommend that you purchase another air filter box for inspection reasons and also a K&N or other cleanable filter as your filter will get dirty faster and moisture, from rain, might degrade the performance of a paper filter.
Air pick up
This is the duct work that runs from the front up along the radiator. It is standard 3-inch intake duct work.
Looking straight down you can see the coupler is rubber. This allows movement and a tight seal.
I can pull my air box off to cross water without confusing the MAF with an open seal in the air box.
Here is a view of the duct coming up. This shows the coupler better.
Here is how I sealed off the end where the snorkel is attached too. It’s a large rubber tire patch held on with a hose clamp.
Here is a straight on view of the attachment.
Here is an OEM air box cover.
You can see where I attached the part that inserts in to my duct work.
It is a plastic 4-inch to 3-inch reducer. I cut wedges out of the 4-inch side and then heated it and flattened it out.