I have one with three corny's and a 10lb tank. Works great.
You could fit theoretically fit 4 ball lock kegs in if you move the tank outside (but I wasn't interested in drilling out).
4 with a 5lb tank on the inner shelf or larger tank outside the box. these all have gauges that need new dials and the hoses run outside. No co2 tanks. Don't wait, you'll be sorry. They all work but some have a few cosmetic issues like small dent's on the top.
i snagged one of these last year with a 20# aluminum tank and a full keg of bud. Deals are out there!
I have the tank outside and changed the tower to have 3 on tap and one carbing on standby. Electric increased 13-15 bucks a month