Yes, much indeed. The manufacturer has full control here, just like different cars’ clutch setups. Between multiple manufacturers (for applications that have great support, like Jap sporty cars), you see different numbers of plates, spacings, diameters, etc. Last I checked, the common break in was something like 30 minutes of pretty much flat out driving around a figure 8 of moderate size, forcing it to lock up in both output directions and under both acceleration and deceleration. I feel like “Geez, so I have to tear up a set of decent tires just to break in my diff?” That and the more frequent fluid changes and eventual plate changes are why I’ve never liked them for street.
Let’s see what JHM comes up with, but there are already several products out there that will fit our car with some adjustment, and a Wavetrac and a Quaife that are drop in. But only if you have the 6MT - automatic cars have a different differential, designed with some different dimensions, likely due to the ring gear being a bit different in size/shape. Presumably, they wanted to keep the pinion shaft in the same bore hole, so they had to move the ring gear, and figured they’d move the landing on the diff rather than anything in the housing. But the housings have different part numbers as well, so no telling. I don’t have both housings in front of me any more, so I can’t measure them. But I do have both open diff’s I think. For sure I have metrics on them, either way, and some solid models on the computer.
