Hartke speakers

Hey guys! Need some info. I blew the 15 in my vx115 hartke cab. Have come across a used vx215 cabinet. Question is... the 215 is a 4 ohm cabinet and the 115 is an 8 ohm. Does the 215 use the same speakers as the 115 only wired in series to drop the impedance? Also would the crossover unit be the same? Any help would be greatly appreciated!