My 1979 244 B21 head is leaking oil and coolant around the the area between exhaust ports 1 & 2 - at the "oval" area in the gasket where high pressure oil goes from the block into the head.
It was a Type "160" casting (number is on the side of the head above exhaust ports 2 & 3) which according to a post is pure aluminium, but apparently later heads (1980+) are of Type "398" and are an aluminium/nickel combination so are more resistant to corrosion. So it seems should I only remove heads of 398 engines at the junkyard. The photo shows a junkyard 1984 B21 head with no corrosion at the head/block junction. Also the water cavities inside show only pink anti-corrosion material precipitation - no pitting.

After finding 398 heads and removing them from the block, should the head surface never be discolored for a good "uncooked" head - only aluminium "silver" color? There are a couple of photos of cooked heads at http://www.pbase.com/stealthfti/goodaluminum but they are discolored only yellow. My junkyard head is discolored brown/red at bottom of cylinder 1 (left side of pic) and blue at bottom of cylinder 2 - what does that indicate? (The yellow "smears" on the top of the head are oil from dragging head over block on removal). The valves appear rusty but the head still had both manifolds attached to keep rainwater out at the yard.

THe poster at http://www.pbase.com/stealthfti/goodaluminum had to go through 11 (yes, eleven) junkyard heads to find a good one! There is not even 11 240s at my local junkyard and non died in a crash. Worse, B21, B23 and B230 heads are not interchangeable. Are good junkyard heads really rare?