What does this box do ?

[steve-V8s]

What does this box do ? found it tucked under the transmission tunnel. seems to have a battery attached.

[steve-V8s]

Ah, yes could be a tracker, would perhaps explain the battery. Looks just a bit amateurish, the battery seems to have been wrapped in insulation tape. It has two wires disappearing into the door lock area, perhaps to pick up a supply and two wires disappearing through a hole roughly above the diff could be the aerial I suppose. No markings or numbers on the box, suppose if it is a tracker it would need to be a bit discrete.
Weighs a ton ( well half a kg) so it is coming out whatever it is.

[steve-V8s]

Alarm sensor is still there so not that. Can't cut the blue wire first because they are all black.

[steve-V8s]

Your theory could indeed be correct Ben it is certainly heavy enough to add some grip purely by being there. I did spin the car several times before removing it however so perhaps it wasn’t working correctly. I guess there must have been a similar device fitted to the Datsun which you also removed.