I am finishing up my build--about to put the head on, but I completely forgot which end of the ARP studs go into the block--the one with the longer set of threads or the shorter threads?

 

I called ARP and the longer threads go into the block--for the newer studs it doesn't matter because its pretty obvious with the allen key recess--but the older ARP studs don't have any hex recess to install--you have to wedge two nuts together to thread them in properly.