If we agree to the basic outline of the John Tate theory, the guitar Ace holds (awkwardly) on the cover of Alive! was a Gibson Les Paul Deluxe that had had its finish sanded down. The snazzy new look first showed up in Toledo, Ohio on March 28, 1975. For those keeping track, if we assume that the John Tate theory holds, this hiatus actually lines up very well with the time when Paul got his Firebird I modified. The Deluxe that showed up in Toledo had a matte, poorly applied black finish, an added (fake) middle pickup, what look like gold top hat knobs, and Schaller M6 tuners. For a couple of weeks in March-April it showed up all over the place but, all things considered, Ace plays it relatively seldom. He was just as likely to reach for the Gibson Les Paul Jr at this time.
That photo from Fayetteville is the last confirmed time Ace played the black three-pickup Deluxe live. Shortly thereafter the gold top hat knobs were swapped for black speed knobs. In a surprise move it's actually Paul that is the last one to use this guitar live. (The three photos above are the only ones that show Ace actually using this guitar.)
As all KISS fans know the black three-pickup Deluxe then featured in the two promo videos from Dressed to Kill and ended up on the cover of Alive!. There is a backstage photo from Cobo Hall that suggests that Ace actually tuned it up before the show, but it never seems to get anywhere near the stage. Instead Ace opened the show with the Les Paul Jr before moving to his trusted tobacco sunburst Deluxe. Considering the outsized influence this guitar probably has had due to its position on the cover of Alive!, it is remarkable how short a period it was even around. After Cobo Hall it disappears completely and is, as far as I know, never seen again.