Head Bolts

I am getting ready to purchase a set of aluminum heads for my 42U. Can someone tell me what the difference is between the bolts for iron and aluminum heads?

The headbolts for aluminum heads have an extended head on them to make it easier to reach them with a wrench to tighten. Threads, length of threads, same as iron head headbolts.
DD

Earl,
I have a brand new, never used set of S&S aluminum heads that I am not going to use.

PM me for more info if you are interested.