Not long before I upgraded to the AUII XR6 I put a new 3.45:1 Diff in my ED Futura. Those quotes you fellas are throwing around are great because it cost be near on $1,000 to have brand new Borg Warner Gears installed. If its an auto you will need to have an electronic recalibrator installed behind your dash to adjust the speedo and odometer. Mine ended up being out around 15 - 18 kmph at 100 k's. Near on $ 200 for this little job.
Be careful because the Diff boys love fitting old Skyline gears instead of Borg Warner or Ford Genuine.
How much for 30 minutes ??