Outer Limits 4x4 Board

So I've picked up some new tail lights for my 40 series, unfortunately the lights i've got are for a '4 pin' plug, the lights in it are a '5 pin'.

The lights came from fleabay so I can't really be bothered trying to swap/return them, my question is, is there any reason I can't just cut one of the plugs off and wire to one that will actually mate up?

And what would happen with the 5th wire, that isn't used on the new lights?

Go for it.

There are no "standardised" 4 pin or 5 pin plug pinouts anyway.

I imagine the original light assembly was using the board itself as the earth through the mounting. Therefore original 4 wires are reverse, indicator, park and brake. The new one doesn't earth through the mount and needs an earth wire to that 5th pin.

Cheers for the replies guys.

Electrics really aren't my area .