Evidence for this is that in realoem (assuming it's accurate), the lsd discs and clutches are the same part number.
https://www.realoem.com/bmw/enUS/showpa ... Id=33_0053
Also, the pinion bearings and carrier bearings are the same parts too.
https://www.realoem.com/bmw/enUS/showpa ... Id=33_0037
I took apart my old sideloader and measured it, it's almost exactly 150mm end to end, which lines up with schematics I've seen. I don't have a spare 188mm from an e28/e30/e34/e36, but if someone does - lsd or open - please measure the length end to end. If so, then it should be a drop-in assuming the stub axle splines are the same count, size and length.
And it seems likely that the ring gear would also bolt up, barring any shape differences. Or, you could use the newer ring gear set as the pinion appears identical.
![Image](https://live.staticflickr.com/65535/53614030353_a06e3bbcd2_b.jpg)
![Image](https://live.staticflickr.com/65535/53614271545_85faf77121_b.jpg)
![Image](https://live.staticflickr.com/65535/53614271345_6e982e4fc0_b.jpg)