What's the sensor on the side of the trans?
 

Noticed a fluid leak on my previously leak-free manual 1985 NA Z31, check and it's tranny fluid, apparently coming from around a sensor that sticks out horizontally of the passenger side, a bit to the front, and pretty low down.

Is that the speed sensor? That kind of what I think but would love confirmation from anybody who knows, my Haynes manual is useless on this subject (although it does list three sensors/switches to disconnect when replacing the transmission, the neutral safety switch, the reverse light switch, and the speed sensor, and on a Z32 tranny this is in the same place as the speed sensor...)

And last, maybe I just have to try car-part.com, but any place where I could find one if it needs to be replaced to stop the leak?

switch for backup lights maybe?

Well I suppose disconnecting it would tell me what it is...

But more importantly, if I can't somehow re-seal it by replacing an o-ring or something, is there anywhere left that carries Z31 parts like this? I work at Autozone and can't find anything in our system... maybe one of the commercial specialists can track it down through their various suppliers, but I was hoping one of the Z car experts here would know.

Thanks!

Well, it's the back up light switch, and I found one that I hope will work on partsgeek.com...

Try looking at part no JA4238 in the Autozone inventory and see it the switch matches. This is listed as the backup light switch for a D21 Hardbody truck w/ the VG30E motor and 5 speed overdrive transmission (FS5W71C). Same drive train as your Z31. The only difference may be in the electrical connector.