XP 60-68:
"The most functionally perfect bow series we have ever designed. Four years in experimental,one year in field test, three years on the market from the cold of Alaska to the heat of South Africa, in 40# weight to 100# weight, no XP has broken or required service.
Maximum speed and limb efficiency, the stability of a tournament bow, minimum tendency toward limb twist, easy stringing, long enough to draw through 30".
Every technical achievement we have developed has been used in the XP to develop greater speed and hold stability. Lifetime guarentee."
These were usually made in 60 and 64. Yours is a bit later when Staghorn customers wanted XP performance in a longer bow. Nice find!