I have a R200 LSD 3.7 has CVS out of a 88 300zxt in my 82 280zxt. I also have a R200 open diff 3.9 has bolt on axles out of a 80 280zx 2+2. I want to change the 3.7 to a 3.9. I was reading about this in some theard a while back but it just said that it might be do able. So before I pay a shop to do it, has anyone done this? Can it be done? Does both diffs have 10 teeth on the pinion?

 

That's a lot of work and money for such a small ratio change... is there a reason you are dying for .2 higher gear ratio?

Swapping the gears is easy, but reinstalling the carrier into the pumpkin is a lot more technical. You have to measure backlash and deal with bearing preload. If you don't get it right, you can break stuff (aka differential parts) while driving. So yes... a shop should do it for you, and I imagine they'd charge $100-$300 to do so.

 

I have already checked on the price they said $200-$250. I really want 4.11 gears but they are next to imposible to find in the R200 from what I've heard. So the next closest thing is 3.9, which I already have. So I'm asking are the ring gears interchangeable?

 

In case you missed this:

Yes. I imagine you need the pinion gear to go w/ it (since they are sold in sets anyway).