The cabinet is wired to 8ohms and the speaker cable output comes out of the 5 pin socket which also takes care of the footswitch , the speaker is a 12" celestion T0731 (g12) . This cabinet can basically transform any head you want to put on it into a vintage souding masterpiece , for most 'vintage tone' lovers this is one of those holy grails.
The 'L' in the Leslie badge must have fallen off at some point,,The vents on the side are indeed designed to let the sound out from the rotating speaker. But instead of the speaker itself rotating, there is a rotating baffle in front of the speaker that directs the sound out of the top, sides and front. Sadly this isn't visible from the photos, and to get to it would involve serious stripping down of the cab.
It sounds very nice as well. Vibrato at the fast speed and chorus at the slow speed. Combined with the right amp you can get that 'George Harrison circa Abbey Road' type guitar sound.
Former Selmer employee Patrick Kirby also reported a Selmer amp with built-in reverb and Leslie, which he says was rented by Abbey Road studios for Beatles sessions. (I consider the Beatles connection apocryphal until a photo turns up, since an actual Vibratone was shown prominently in "Let It Be".)