I was doing a brake job on my 240SX yesterday. Jacked up the rear by placing the jack under the rear differential and thought I would compare the differential to my 350Z rear carrier. They look like exactly the same model. The 240SX has a 4.08 rear end gear and some come with viscous LSD. Diff's from a Z32 N/A and Infiniti J30 are the same, I believe, and come with LSD standard.

My 240 doesn't have LSD but I think I'll be getting an aftermarket unit for it and swapping the diff's between the two cars. For anybody wondering, the lower gear in the 240 will give the 350 better acceleration since it comes with around a 3.6 ratio (or something like that). Yeah, the acceleration in the 240 will suffer but it's my wife's car. I doubt she'll notice the difference.