The transmission in the J30 is the same as the 300zx NA (RE4R01A)
the transmission in the q45 is the same as the 300zx tt except for a friction
(RE4R03A)
Rebuild kits are the same number for the J30 and 300zx
Different kit numbers for the Q45 and J30
The J30 ECU is a 16 bit and the pre 93 300zx is 8bit (8bit have a removable eprom) with the 16bit to upgrade you must either use a daughterboard with a 512K chip or you can do a Nistune upgrade and will interchange with the right rom file which you can get at
www.aaa-hiperformanceauto.com plus they handle the built autos