The R160 is MUCH smaller than an R200. The Silvia will have CV jointed shafts like the Brumby but the size and design will be different.

On an R160 the two splined shafts that go into the sides of the diff are the same length and on an R200 they are different left and right. Also the R200 is wider than the R160 so the length of the driveshafts will vary, especially the left side.

The method for retaining the axles into the diff is different too. the Subaru diff will have bolt-in axles and the R200 will have snap rings.

I think the later, facelift Z31 Nissan 300ZX might have come with an R200 LSD but I'm not sure. Most other cars that came with LSD R200's used the Viscous type unit, housing in a different design casing that won't fit. I believe it is possible to build the internals from one of these into your R200 but you will still need to do some work with the driveshafts as the viscous diff requires special driveshafts. Late S13 and S14 Silvias and 200SX (180SX) have these VLSD's.