i just happen to have an auto trans partly apart and can show you , its where the wires go inside the box to work various solenoids for shifting , overdrive and oil temp etc , to remove it you will have to drop the pan unplug the wires and carefully push the 3 tabs that are on the inside of the box in to release it be a lot more easy with the valve body removed , pics show with the valve body in place and with it removed , hope this helps.
Awesome, great pics thanks! Edit: Also, is it necessary to unplug this if dropping the trans to replace rear main? Or can I just leave it connected because it has some slack?
Ok first up i will point out that the car we have has wayyyyy more room around the box to move than a normal 300zx because its this car http://www.aus300zx.com/forum/showthread.php?t=322798 now that said i've pulled the box with all the wiring as in the photo you put up, there are 5 plugs you have to undo the gray one you can see in the middle of your pic as well as the brown one thats hanging down in the pic near the rear cross member but it lives near the gray plug when its in its right place , now the wires that are heat wrapped and hanging over the back of the box in the pic have 3 more plugs , this part of the wiring go's up behind the motor into your engine bay and end up beside your hicas valving if you still have it { near where you fill up your window washer water } undo the 5 plugs and drop the lot out , but if your doing the rear seal where the tail shaft go's in you'll be able to do that with the box in the car but if its the front seal the box will have to come out ..
