Was looking around on my local Craigslist and saw this ,I haven't seen one like it,kinda cool! http://kansascity.craigslist.org/msg/4828046375.html
That cab had 12's in it, not 15's, and they were pretty low wattage, low X-mass, small voice coil guitar speakers. I've seen a few of these, and all I've seen had broken glue joints on the baffle joints, and attempts to repair with substances like silicone caulk. A customer cleaned up and reglued one, and replaced all 4 speakers with Jensen C12K speakers. He wanted to use the cabinet for guitar and bass. He was thrilled with the results. Since the original speakers only had to handle 100 watts, I guess Fender decided low watt speakers would work. But they were easy to blow, so there aren't many with 4 intact stock speakers. The cabinet looks in not great shape, and he neither shows the grill or mentions it. I've seen these cabinets go for $100 in better shape.
There was a thread about these cabs on here several years ago. The consensus was negative. I love vintage gear and had a Bassman 100 head, so when I saw one these cabs for sale near me, I went and checked it out. Unfortunately, I then had to agree with the consensus. Not to good, and as Steve alluded to, a real beast to move. I sold the head and found a '68 Bassman (50 watt) head and matching 2x15 JBL D140-F equipped cab. Perfection.