Customers van sat on ramp.
Customer says rear diff lock doesn't work.
Simon says diff lock does work, but light doesn't come on.
Simon has a look.
Simon notices someone has had a right "go" at some special wiring.
Simon removes switch, finds it's all mullered from previous attempts to attach some wires to broken stubs of brass.
Simon tries to order a new switch, which he is told is not obsolete, but non in country and on back order.
Simon says "oh, bums"
What to do?
Van on ramp, lots of money tied up in it, no news on switch, must make light work.
Simon goes hunting in the stores...

Simon comes out with M18 sump plug and a T3 reverse light switch.
Simon goes to see matey at machine shop across the way and gets him to whittle down said sump plug and tap it to m12x1.5 down the middle.

Simon then thread locks the switch into the chopped down sump plug, repares the "special wiring" and jobs a good 'un.
Just thought I would share incase anyone else is in the same boat.