Have done mine with some repro parts. Got tired of looking for the OEM as it was stalling the project. As I trawl Ebay and swap meets etc I find the OEM parts then restore the item and fit to the car as required. Absolute exactness cost a LOT of hard earned cash, especially when you HAVE to have them. For Example found an Holden V8 OEM thermostat housing at a Swap Meet last week, Paid 2 bucks for it. Simple after market did the job for the last 6 months.