We recently broke the rear diff in my mates STi6 group n rally car. On stripping out the diff, we found that it had ripped itself apart. ANyway, the thing is that it wsn't the type we expected to find and neither of us know what sort it is.
Its a 160mm crownwheel but its not plated and its not viscous. On removal (it fell apart to be exact) inside the diff mechanism are loads of trapezoidal "teeth". These seem to sit in between two multi angular faced "plates". These are the parts that the stubs from the driveshafts fit into.
Does anyone know what type of diff this is? We've asked a few people and no-one has come across this type before. I suspect that the original diff was exchanged by the muppet who originally started to build the car.

We have now located a R160 to replace it but we're curious to know what it is. Cheers, Mark.