Can I install the Turbo II transmission into an NA?
Certainly. But you need to also install:
-TII flywheel, clutch, pressure plate
-TII slave cylinder
-TII starter
-TII driveshaft, differential, axels
-Adapt the wiring.
MazdaTrix (
www.mazdatrix.com) makes a TII transmission to NA rear end driveshaft, so if you don't want to swap your rear end, you can use that shaft instead.
Can I install the RX-8 6 speed transmission into my 2nd Gen RX-7?
5th gear on the FE tranny is the same as the 4th on FC trannys anyway, so there is no real advantage of using the RX-8 tranny, and 6th on the FE tranny is actually taller (.83 vs .71) than the FC, resulting in lower gas mileage at highway speeds.
Using a RX-8 tranny would be like adding a extra gear between 2nd and 3rd to a standard 2nd gen RX-7 M or R type transmission.
Add in, that the RX-8 6 speed transmission is also about 4 inches too short, forcing you either to relocate the shifter 4 inches forward in the car, or move the engine 4 inches backward (towards the firewall) to make it fit in the stock shifter location.
Did my 2nd Gen RX-7 come with a Limited Slip Differential?
Only the following USA model 2nd gen RX-7s had a LSD from the factory:
86-88 GXL
87-91 T2
88 GTU
89-90 GTUs (however not the 89-90 GTU)
It is also rumored that a few rare 91 coupes with both the A (upgraded the interior trim, added a power sunroof, tilt steering wheel, cruise control, and 4 piston front disc brakes and vented single piston rear brakes) and the B package (leather seating, a CD player, and rear cargo cover) came with a LSD, but you should note that Mazda denies that any FC other than the T2 came with a LSD in 91). You can also tell by looking at the differential as there will be a LSD tag on S4 cars with a LSD.
Non US models with LSD info to come