Diff Loc engaged?

How do I tell if the Diff Loc is engaged without depending on the diff loc light in the dash?

Thanks

If you can remove the centre panel, you can see the position of the arm on the transfer box. Just google "defender transfer box linkage" to get a picture of how it should look. As you move the transfer lever to the left, the linkage makes the lever on the box move to the right, engaging the lock. If you mean with the wheels, all off the ground, turn one of the fronts and see if any of the rears turn.

Engine off leave truck in gear, jack a front wheel off the ground, if it spins then no diff lock, if it's locked than its in diff lock. Simples.

Awesome, thanks guys !

It does not seem to be engaging, I didn't think it was, the light is not coming on and the shifter does not feel solid.

Got mine fixed! The guys that changed my clutch figured it out.
Badly out of adjustment.

Just slip it in to difflock every now and again to keep it nice and free working