Ben: No, it's definately not a TRX diff, because I used your RA40 carrier in it for awhile. The RA40 axles I got from you are exactly the same as the axles that are in the car, except they are 30mm longer. Same splines and bearings and everything else. Apparently RA23/28 axles are shorter than RA40/60.
Measurements I got from my dodgy tape measure, from flange to end: