I will be needing to replace my heater core soon and want the best heat possible, which gives better heat ? I hope to do this job once and never have to do it again after reading about how much work is involved. AutoZone shows a Copper/Brass one for about $45 and Aluminum for about $25, what are the pro's-con's of the two? Should I just spend the extra money on a Motorcraft heater core, they seem to be close to $90? Any brands to stay away from?