BOFU replacement for Pass TL

Years ago I built a pair of the Pass TLs and put a pair of Pioneer BOFU full range drivers in them. I used them for a while and then built something else and gave them to a friend for his living room but he went and got married and his wife banished them to the garage, where they languished. More time went by and I got them back, but at this point one of the drivers is FUBAR and I have no spares. Has anyone a suggestion for a new woofer that will fit in the same hole and has specs suited to the transmission line? Doesn't have to be a full range driver. I could try a woofer/tweeter/crossover setup this time. What might work?