Thanks Chas so much for dig down to find information and post photos. I realized that I made big mistake. I thought I was rebuilding 280zx FS5W71B transmission, but it end up 200sx or 720 truck tranny. Syncro difference btw closer ratio and wider ratio FS5W71B - Drivetrain - HybridZ So, I start rebuilding '77 FS5W71B (wide ratio, early 71B) that I pulled out from Junkyard. I realized that I need right hand thread of mainshaft nut for this tranny after searching web. 5 speed Transmission Nut numbers- Gather Car A&Q So, the mainshaft nut part#32354-E9803, I got, is actually left hand thread. I need right hand thread of main shaftnut, which is part #32354-E9802 or 32354-E9804. I just ordered it at local Nissan dealer and will be there this Saturday.