Speedometer Sensor

AK recommend a sensor fitted to the rear of the chassis, next to the propshaft to differential flange.
The idea is that it fires when one of the nuts securing the propshaft passes by.

The air gap between sensor and nut is ~2mm. The nuts need to have their edge facing the sensor as they rotate past. If one or more have their flats facing the sensor at their closest approach, there will be a greater than 2mm gap and we'll get dodgy readings.

So make a bracket and fit the sensor.

You may want to do this before fitting the propshaft and fuel pump if your pump is nearby.
Makes it easier to drill and tap the holes for the bracket.

But. It turns out that the Tremec box I have from Roadcraft came with a fitted speedo sensor and a wired plug. This seems to be a more elegant solution. If you don't have one, probably cheaper to go with the sensor from AK on the flange nuts. I'll use the gearbox one, so the above bracket isn't necessary on this build.

Speedo sonsor and wired plug on the offside of the Tremec 'box.