problem identifying correct heater hose part on 2003 Ford Taurus

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I have a leak in the heater hose of my 2003 Taurus. It is the hose that goes from the thermastat housing and wraps around behind the engine and goes to the firewall. about 14" is rubber then it changes to a steel tube. The leak is in the bend of the steel tube. I cannot seem to be able to locate a replace part. The enineering no. printed on the rubber hose is xf1h-18k579-aa. The ford dealer i went to has not been of much help locating what part number i need. Any suggestions?
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I have a 2000 Taurus wagon with the DOHC engines. There is an assembly with no less than four rubber hoses pre-attached to three interconnected (by welds) metal tubes that replace as a unit. Part number is YF1Z-18B402-AA. My NAPA store referred me to Ford. My Ford dealer keeps it in stock, and says he sells a lot of them. Charged me about ~$91 + tax. Google/Images that part number for more information, including how to install it.
Try a Napa store. Sometimes the dealers have rookies at the retail counter and they are just learning themselves. Napa uses Gates as a hose supplier which is an OEM factory level part. A 3.0 heater hose for a Taurus should be an available part.

I need to know if the engine is the single or dual overhead cam design. So, what is the 8th VIN character?( gives the engine code ) I have found several Ford dealers on Parts voice that have ALL the hoses for your vehicle. Maybe this can help. I usually use Napa first for domestic cars , because they have really good parts and are much more reasonable.

I still have not given up on Napa. A good store should be able to outsource the part, even from a dealer. I have it done on a regular basis but I live in the Bay Area which is a big market.
I went to a NAPA dealer initially about this and was told that this was a dealer part.

It is a single overhead cam and the 8th digit ov th VIN is 2. I live in a very rural area and the dealerships are small (both ford and napa).