Here is an Ebay auction for a used C5OE thermostat housing by Ebay member "threegorillas" with a Buy-It-Now of $80.00:
OEM FOMOCO Used 1965, 1966, and 1967 Ford Mustang, GT350, Shelby, Falcon, Fairlane, Ranchero, Bronco or Mercury Cougar, XR7, Comet, Caliente, Cylcone, 289 2V / 289 4V HIPO Aluminum Thermostat Housing / Water Neck. Part number cast into it is C5OE-8594-A or C5OE-8592-A (WE BELIEVE - PLEASE SEE PICTURE TO CHECK FOR YOURSELF). Straight out of the blast cabinet, so what you see is bare metal. Condition is good for the age, but there is some pitting as shown (typical for aluminum exposed to antifreeze). What you see is what you get, so please look the pictures over and judge for yourself! AS WITH ANY ITEMS, NO RETURNS ACCEPTED. Shipping to continental US is free, but please allow a couple of days to get items to the post office. Please let us know if you have any questions, and thanks for looking!
1965 1966 1967 Ford Mustang Shelby Fairlane Cougar ORIG 289 THERMOSTAT HOUSING | eBay
-Fred-