Mystery R200V

[Kallikak]

Well, I have an R200V differential that was included (not installed) with my 240SX. From what I understand, the ones that came with 240's from the factory had 4.083 ratio (49/12). My spare diffy has a 3.91 (47/12), which would indicate it was from a J30. However, it does not have the ABS sensor; it is my understanding that all J30 diffs would have the ABS sensor with the 47-tooth ring gear, and all 240SX diffs would have 49-tooth ring gear. My diff has the 240SX style six-bolt output shafts, if that matters at all. What on Earth is mine from then?

More important than that, how much of a difference would the 3.91 ratio make compared to the 4.083 I have stock? I really don't like the idea of changing gear ratios because of the speedometer error, unless there is a way to re-calibrate the speedo.

Also, is there any way to determine what kind of shape the VLSD is in on the bench? I tried to hold one output shaft while turning the other; a good deal of resistance, but I could turn it ever so slowly. I'm inclined to think that's a good thing.

Thanks.