Just picked up the last of the parts for a rebuild from the machine shop.

Piston pressed on the the rods and all that stuff.

I was taking the heads out to the truck and the man in the shop asked about the 041's I had.
Not really having any idea what he was talking about I sorta let hem keep on going, he went on about how rare they are and that just 10 mins before I picked mine up he had a guy wanting to buy a set.
Someone enlighten me on these heads.

What are so appealing about the "041" heads?