It's a very easy swap. Take out the whole fan shroud, take off the bolts holding the fan onto the shroud, unplug the harness, and voila!...there you are. Repeat backwards for the install. I'm sure just about any auto parts store has it. I'd shop it around first over the phone though. You'd be surprised at the price differences for the exact same part from store to store.

If it were me, I'd change out the thermostat too. If it's been there as long as you say it has, it may nearing it's life expectancy. It's also an easy and cheap part, but one that can cost you 50x's more if it goes bad out on the road. It too is a 15 min job. It's easy.

Good luck. Hope you get it fixed for good.