I used the copper gasket because that's what the guy at NAPA handed to me from the gasket and washer section. I personally would not use nylon as there's a lot of heat and the torque you have to tighten down on these bolts can easily squeeze a nylon washer out of proportion. Aluminum might work, but again, i personally believe copper is better for a gasket and washer.
But again let me say again, that make sure you use a power tool to tighten down those bolts, you will not strip it, and tightening down with your hand on a wentch didn't give me the torque needed to seal the bolts and washer from NAPA. I had to use the impact gun atlease 3 times to tighten it down, each time I could see the bolt move til it stopped. I almost returned the radiator because I thought it was a faulty welded one due to the leak.
Here's some pictures to entertain you guys of what happens when you warm up the engine and spray water around there to wash away all the coolant.. you get something that other people might think that your car is seriously overheating. heh heh heh..
-Larry
