Black Short Two-Piece &
Elvis usually used black pants with red leg insert to this jacket and pants without leg insert was probably also used.
The belt used for this suit is called "Metal Concho" and it is a leather belt with big metal jewelry with small turquoise rhinestones around the edge. This is a well known belt in the Elvis World, and it was used in private on the set of Stay Away Joe and also on the rehearsal in August 4th 1970 at the International Hotel, to name a few occasions (see photos below).
From time to time Priscilla would travel to New York, looking for jewelry and belts for Elvis to wear in private and sometimes at his performances, much like the "Metal Concho" belt.
Elvis used a number of different scarves to "Black Short Two-Piece Suit & Chest Pockets" or "Black Two-Piece Pocket" suit. Hopefully this suit exists in the Graceland Archives, but it has probably never been exhibited.
Elvis Presley, Fashion for a King, by Tommy Edwardsen and Atle S. Larsen (Follow That Dream)