I see a part# P3690589 according to the old SA Design “Mopar Performance” book on the parts outline page they list it as “Magna-Velocity” with 324° duration and .670” lift for the SB. The RB section shows P3690588 with 332° duration and .695" lift which is referred to as “Super-stock” I can’t recall when the Mini-Express was offered, maybe in the early 80’s??
