As he said.. and i think the import diffs are viscous as well ??
Best bet is just an aussie R31 w/ LSD (bit rare) or VL turbo.. All Skyline Silhouette
models come with them so if you can track down one of them (difficult) you'll get a nice LSD. TI's also are more likely to come with LSD, but not all come with them.
Don't XR6 (or is it XR8) also come with LSD available as an option?? In fact when I asked recently, most R31 guys recommend looking at an XR6 or XR8 to find an LSD centre due to easier availability.
Unfortunately.. they usually tend to put poxy low ratio diffs in the aussie cars while 3.89 is nice, 4.11 is better
I've got a bit of an interest in this, as my diff in my r31 is getting a new centre put in thursday. I was going to go LSD, but unfortunately the cost, and even just finding an appropriate LSD centre was pretty hard.
Actually, seeing as your in QLD, you could always call the guys mine is getting done at to find out your options: NERANG DIFFERENTIAL SERVICES PTY LTD : (07) 5596 4963..