Hmmm. I could be wrong and I don't mean to cause alarm but it kind of looks like a keg set up for cleaning beer lines etc, but I'm not sure. You make have to buy ball lock posts to fit into the keg (removing the ones on it), as it looks like a Rheem or Mytton keg your going to have to try kegsystems.com.au, estimated at around $20 each for the posts as these kegs are pretty old and parts are scarce. Guess you'll just have to wait until it arrives and see what you've got.
Good luck though, I hope it turns out. Just for future reference too I think kegsystems still sells 18L kegs for about $70 each and he's in NSW. Either that or an order from brewersdiscount for about $50 each delivered.
Cheers, Justin