302 heads

went to the pull-a-part today to try to find some rocker arm assemblies for my engine.I only had 2 trucks to chose from,both had 318's,both had 302 casting heads,both were rusted and milky on the top end.I,ve herd that the 302's were bad about cracking,might have just been a coincidence but I'm out.still need some rockers.go searching on another warm day.:realcrazy: