The fan clutch is operated via a solenoid controlling power steering return fluid pressurized at approximately 100 p.s.i. A bulkhead fitting (Fig. 178, Item 20) 4730-00-897-5497  is utilized to transfer the fluid through the fan shroud.
Looking for a cost-effective substitute, we determined that this fitting is also marketed as a brass fitting called a Bulkhead Fitting, with the dimensions of 1/4″ NPT x 3/4″ long.
When we sourced this item, it came in a package of five. The price for all five was just under the price of one from a larger parts distributor, and we now have four extra on the shelves.