We obtained a complete fording intake stack from Alan Post. By complete, we mean the stack extension 2510-01-198-0333 , the clamps 5340-00-079-7837 , the vent tube 4710-01-209-6746 , and the windshield mount bracket 5340-01-238-9543  with fasteners.
As you may notice, the rubber extends a little higher than normal at the base of the stack. We had ordered several 4 1/2″ silicone 90°s, to see how they would work. As it turns out, the actual AM General part is slightly less than 90°. Use of the silicone 90° required cutting the end that connects to the air cleaner at a slight “off-angle,” as did the portion that connects to the stack. We have instead ordered the correct fitting to replace this, however use of the silicone 90° would definitely be adequate and completely serviceable.