I want to fit a reverse light switch on the buggy. There is a plugin on the nose cone of the gearbox where I think it goes, feels like an Allen key should fit it. Any one got any idea what size key will fit ? I'd prefer not to have to take the gearbox out if possible 

Not sure what size key it is, but I know it can be done with gearbox in situ, as I did mine many years ago

It's either an 8mm or a 10mm and can be done in situ

you can do another way,ihave hella nos reverse switches for 6v cars.it fits inbetween the speedo and the cable.as the car goes backwards it closes the switch light goes on.

you can do another way,ihave hella nos reverse switches for 6v cars.it fits inbetween the speedo and the cable.as the car goes backwards it closes the switch light goes on.

that would be great, but I've got an electronic Speedo. The engine is out at the moment, so I might as well take the gearbox out as well. There's someone on a local forum that has a spare nose cone with the switch already fitted, if I can't get mine fitted. Are nose cones interchangeable on different age boxes ?

Pretty much yes... But if your taking the box out then fitting the switch is even easier. You just need a live from your coil with an inline fuse to one terminal on the switch then the other terminal on the switch goes to the reverse lamp, then an earth from the reverse lamp. Done.
With the engine running, you engage reverse and lights come on. This way if you leave it in reverse (for what ever reason) when parked up the lamps have no power, no drained battery.

Great source of knowledge on this forum from a lot of really helpful enthusiasts 😀

Box with switch fitted




But really no need to take box out - access is pretty good in situ