I never saw a factory 5.2 or 5.9 magnum head with press in studs. I do have a set of heads on a 360 magnum that I got used in the mid 90s that looked like it had pressed in studs, but upon closer inspection it turned out to be the Crane conversion studs that are threaded but do not have a hex, they use a jamb nut for installation. Look up Crane part number 36655-2. I think that is what it has and you can see them. Also, those Crane studs use plastic pushrod guides so hardened pushrods are not required.