Well if I can remember it's not all NA 89-90 RX7's the 4.30 with LSD was only in the GTUs not the GTU or any other NA model. If you got your hands on the whole differential just swap it, buying the ring & pinion is not that hard if you are mechanically inclined. I'll see if I can find a write up on this for you. Also Mazdatrix sells a 4.77 & 5.12 ring & pinion set if the car is not going to be street driven all that much & top speeds are of no concern. Would be great for drag racing.

can I use my lsd with a 89-90 ring and pinion gear cos I dont want to use the viscaus lsd they use or are there any 89-92 that use a 4.30 and a clutch type lsd

You can use the ring & pinion.

awsom ill have to find an 89-90 diff.

Make sure it's a GTUs to get the 4.30 ratio.

are gtus the only one with the 4.30

As far as I remember yes only the GTUs not the GTU or any other model. I think all the rest are 4.10 ratio unless they were automatics & they have 3.90 ratio

a 3.90 sounds like it would have relly good exelleration will that work in my car

3.90 ratio is working in the wrong direction if you are looking for acceleration. Higher the ratio the quicker the acceleration & lower top speed. The lower the ratio higher top speeds but slower acceleration. The 4.10 that you have is better then the 3.90 for acceleration & the 4.30, 4.77 & 5.12 ect are better over the 4.10's for acceleration.

o does 3.90 mean 3.9 . I gess ill just stick with the 4.30 then will I see a big increas in acceleration