Bret,

I'm not at all familiar with a 99 C70 but I consider myself an advanced backyard machanic. The heater core job on my 850 was ridiculously easy. A used core cost me $90. The whole thing took me about an hour. An invaluable resource is http://www.alldatadiy.com. For $25, you get a year of use of the dealer books and technical bulletins on-line. You could buy a subsicrpition and check it out yourself to see how hard it really is. There plenty of illustrations, pix, time estimates, part numbers, and special tool call outs. They will have just about everything you will need to know for your car (also preventative repairs they issue in bulletins to the dealers!). It has been a very well spent $25 for me. Good Luck.

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