So I have my 5.0 , T5 conversion done and I am running the stock rear axle with a 1983 LSD with the 3:90 gears in my 1980 street car. As expected 1st gear is useless with the 3:90 ratio. I have been researching possible r & p sets that would get me a taller ratio and I am confused by the information out there. Is there anyone that can tell me what ratios are available for the 83 housing and where to source the gear set? It seems that a b2000, Miata or Kia might be a source but I don't want to chase parts down to find out they won't work.

 

The lowest ratio, which I suspect you want to go to, was the 3.63:1 they were found in the 80's model 626 or there is also a 3.63:1 that came in the Miata but they were an Australian and Japanese release and the USA Miata owners are wanting them all the time so they are not cheap.

If you want to go higher..... ie 4.10 or 4.30 or 4.44 ..... you could try for a 4.30 from a 1.8lt Miata.