Could be a BW 1501 or a BW 1505. With it having the later-model larger diameter vent in the center of the magnet back plate, I would guess 1505.
Though, it is still a "round arms" frame (later Peavey baskets had squared-off basket arms like in the picture below), so it could be a 1501 still...
Picture of a middle-years 1505 (the newest ones have a black basket), for reference:
The 1505 is more desirable than the 1501, because it has a longer voice coil winding (greater X-max- the coil in the 1505 is about .7" winding length, giving about a 5.5mm X-max, as opposed to 0.55" or so winding length for the 1501, giving about a 4mm X-max).
BTW: Those BW woofers can be reconed with a custom aftermarket kit, with as long as a 0.9" long voice coil winding. That gives about a 8.5mm X-max. That's getting into subwoofer territory.