cheers,

that would make sense.

looks like im stuck with a 3.54 for a while! I'll check it out manually later to see for sure.

2many, on the 3.90 R-180: 720 4x4 1/83-6/83 is that the front or rear diff, or are they the same? A follow-up question is that diff a drop-in swap or do you know if there is other work/parts required?

The 4x4 diffs are out of the front, as all the Nissan 4x4's used a solid axle in the rear as far as I know.

The casting marks on the casing should be 38311-U3000. The Maxima, Z, 810 and the 720 4X4 all used the same casting number on the diff housing which indicates the larger 115mm ring gear. I don't know for certain, but it would seem likely you would have to swap the axle flanges on these, but otherwise it would be a straight bolt in affair.

The later 85 and up 4x4's used an R-180 as well, but these will not work as one side of the diff housing was extended so that they could use equal lenght half shafts.

BTW, the casting number on the 180 housing with the smaller 110mm ring gear is 38311-78500.

2many, you are an encyclopedia of knowledge!! Thank you for the additional info.

Originally posted by 2ManyZs

...I don't know for certain, but it would seem likely you would have to swap the axle flanges on these, but otherwise it would be a straight bolt in affair...

Oh, I just thought of a stupid question as I am still quite new to all of this. The axle flanges, these are somthing on the outside of the diff on each side where the axle attaches. Yes? And you would have to swap them because the diff was in the front and will not be in the rear therefore the left side is not on the right side and visa versa, correct?

Yup, the axle flanges are what the driveshaft and half shafts bolt onto on the outside of the diff.

What is possibly different is the bolt circle between the 240 driveshaft and half shafts and whatever the vehicle you took the diff from. If they won't bolt up, the only thing you have to do is to swap the flanges off the original diff over to the new one as they should be the exact same except for the flanges. I've been looking around but can't seem to find any definitive answer as to whether or not they are different flanges or if the 240 shafts will bolt right on...

Guess the best thing to do is for me to go to the junkyard and find a diff and try it myself one of these days and then we'll have an answer unless someone beats me to it....