90 n/a-T conversion...Which diff do I go with?

[GringoEJS]

I searched and read pretty much EVERY diff thread, and still I don't know what does what. I just did a n/a to turbo conversion on our 90 Supra. I have an 89 Turbo 5-sp diff sitting in the garage, a 90 Turbo AT diff in the parts car, an 87 Turbo 5-sp diff also sitting in the garage, but a 90 n/a diff still in the car. I am basically wondering the pros and cons of each diff. I definitely want to put one of the 3 LSD diffs on the car, just don't know which one is right for us.
Again, we have these diffs available: 87T 5-sp, 89T 5-sp, 90T AT.

 

[drjonez]

clearly you neglected to really read. here's a real rundown:

http://www.mkiiitech.com/forums/viewtopic.php?t=40

based on your list you only have 2 different diffs- a a 3.91 and 2 3.73s. ratio depends on what you're going to use the car for, the lower (numerically) the ratio, the slower the acceleration and the higher the top speed (and obviously the lower the cruise RPM).

personally, i think the 3.91 is probably the best compromise for 90% of MKIII owners out there....