Oh, Elvis

My gym makes protein and health shakes and each month there is a new shake-of-the-month.  This month, that's the Elvis shake.

Would that be the 1950s Elvis, sleek, smooth, and at the height of his fame?

 Maybe it's the soft, drug-addled Elvis of the late 1960s and early 1970s?

 I'm assuming it's not the stoned, heart-attack-on-the-crapper Elvis of 1977.

I've not had the shake --- and I won't --- until I find out which Elvis will appear as a consequence.