P83 is one of the pheros that sits in a class of its own and there is no direct alternative.
P103 is maybe the nearest for physical disinhibition and is the one I keep as a standby for when P83 is in drought but its harder-hitting and not nearly so smooth, so more liable to backfire on you and have the subject suddenly draw-back. It also stinks of ripe cheese to many guys.
P83 is in MX353 at a fairly healthy dose and while back, John confirmed it is in A314 as a steering molecule and as P83 actually appears in a majority of the released MX formulas, I reckon it could well be in several more consumer products.