Need help identifying an R33 diff - clutch or viscous?

[soreballz]

Ok, so I have a diff that is out of an R33 Skyline. It already has the output shafts to bolt right up to the S13...
Thing is, I don't know if its from a GTS-T, which is viscous, or from a GTR, which is a clutch type. I've gotten different answers from several people that knew the cars previous owner. I'm about to install it, and I'd rather not risk putting the wrong fluid in it.
Is there any way to tell what type it is by looking at it?

Here's a pic:

http://www.imagestation.com/picture/sraid215/p42f8a6d9b101209162c1b2b4cdf7b477/ecd6b2ff.jpg

Thanks in advance guys. This open diff nonsense is getting on my nerves. lol

[drift freaq]

Lyle whats the ring and pinion on it? You can tell because the GTST had a different rear end gear ratio than the GTR.

[soreballz]

Not sure. How do I check that? Just count the teeth or what?

[LB.Motoring]

The sticker was lost huh >_< so ez when it has the orange sticker on the housing

I use a r33 Vlsd on my daily s14