I found a small block chev with a thin balancer and what appears to be factory aluminum heads. They were rounded like a factory g.m. head on the ends, and I can't recall if there were accessory mounting bolts in the heads or not. I am thinking not. I have read about a 283/315 horse motor that got aluminum heads for a short time, but had porosity issues. I could not find a casting number, or picture of them. Can anybody help me out? I am going to try to look at it again, and if it looks like factory heads, buy it. Any estimate on value of heads if they are the early aluminum g.m. heads? I also dont recall if it was a single quad or dual quad motor. Any help would be appreciated.