I'd really hate to hear about that nice, powerful 302 blowing a head gasket due to a shoddy junkyard radiator that gave up the ghost 2 miles from the next interstate exit.
I'd choose a QUALITY aftermarket radiator. 3 or 4-core. No less. Even if it costs $300+. I replaced my stock "hotwheels" radiator in my '66 stepside after running it for a year, constantly bringing the temp gauge up over the halfway. Now the temp gauge STRUGGLES to make it 1/4 way
-ftyler
