Thanks Mister Two,

I'm guessing plated LSDs are 'hellical'/mechanical?

And my MY00 WRX would have a 3.9 R160 viscous rear?

I am keen on fitting a LSD rear... there is one going cheap at the moment, but I want to be sure it's what I'm after.
Apparently it's off a 97 STi RA, and was fitted to an 04 WRX.
I know the V3 RA had R180 gear, so it cant be off that (unless he changed shafts and hubs), but the V2 had a R160 plated with DCCD...

I will have to check the bolt spacing to establish if it's R160 or R180... but is there any way I can check for viscous vs plated without opening it up?