It's in an area generally referred to as the "Ship's Graveyard"
in Bass Strait offshore from the Surf Coast. Sorry, I can't give
you GPS marks -- they simply aren't published. There's a site that
has marks for some of the wrecks in the graveyard, but only those at
recreational depths of 40 metres or less.

There's a rough map and marks for the shallower wrecks at:

http://www.vicshipwrecks.com/

I dived the Casablanca last Sunday in 57 metres -- first time on mix.
We used air for travel gas and switched to mix at the bottom. My
initial thought was, "I wasn't narced..." But then I realised that
I'd spent nearly half a minute sorting out which dog-clip was which
so that I could put the primary in my mouth. (Ummm... guess I might
have been a wee bit narced after all.)

But this was another great dive. There are photos on the Scuttlebutt
site. The viz was around 15-20 M at the bottom. For local diving, this
is nearly as good as it gets for viz. Another good wreck. This one has
the helm still intact and visible near the stern. Unfortunately, with
air instead of EAN50 for deco gas, we didn't have time to look at the
section of bulkhead that still has portholes in it lying off the
starboard side. But that's something to look for on a future dive.

We did a wall dive in the "Lonsdale Canyon" near the Port Phillip
Heads for a second dive. Didn't see a lot of the scenery, which is
generally good -- lots of big sponges, gorgonians, blue devils,
scalyfins and other fish. Instead of looking, we spent the dive doing
drills. Shutdown right post, shutdown left post, get spare mask,
etc, etc, etc. Not a "fun" dive but a necessary part of the course.

Summer, ya gotta loved it...

-Don