I don't know if anyone has done this before but I have my 06 G35 5AT with me in the UK and I wanted to swap out the stock 3.3 FD open differential for a 3.5 FD VLSD. Not easy to pull one from a 350GT or G35 because they aren't sold here so not many broken cars to pull parts from. So what I did is buy a VLSD and Diff case from a broken UK Spec 2004 350Z touring. Pretty basic swap. I did everything using a 4 point lift. First I removed the exhaust pipes from the mid-pipe to the muffler. Disconnected the drive shaft from the diff and disconnected the rear axles. Unplugged the TCL plug and disconnected the hose and clamp from the top. Finally, I disconnected the case from the bushings. I drained the fluid out of the "new" differential and put 1.5 qts of 80W-90 gear oil into the diff before I raised it into place because I don't have a pump on hand. I used a hydraulic lifter to put it in place. Took a while to get it fitted into the space due to limited space to adjust everything. It would be much easier to put it into place by removing the rear sway bar. Finally got everything mounted and bolted down. The total swap took about 2-2.5 hours. I'm draining the diff fluid and replacing it with Royal Purple 75W-90 after it arrives in the mail with my pump. I feel the biggest difference in my 3rd gear pulls. It doesn't seem to have effected my speedometer and I don't know how it has effected my MPG yet. Ill post more results of this swap as I have more info.

 

Here are some more pics of the swap

 

and some more

 

Nice upgrade how is the diff temp with the finned diff cover installed.

 

I'm not 100% sure yet but that was one of my first questions I asked myself. I don't have the royal purple fluid in yet so I have been trying not to push it too hard yet. My next track day will be on the 16th so it will truly prove itself then. After my last track day on the 18th of June my two biggest things I wanted to change is throwing out the open diff for a VLSD and putting in Stainless Steel brake lines. The lines are getting shipped in right now with my gear oil.

 

Initially I planned to rebuild the case with a NISMO case and new bushings and seals. Now, I think I might just get the whiteline bushings and skip the NISMO case because this one is already vented. This diff only has around 45k miles on it too so I can wait a little while on new seals.