Today I fitted the US spec rear lights that I procurred on Ebay to the Grizzly.
Although the casings appear the same there are subtle differences, the UK ones are held to the body with three self tappers, the US ones have three captive bolts so the original holes have to be made bigger.
The UK lights have four wires, indicator, tail, stop and reverse - earth is via the bolt / screw to the body.
The US ones have only three wires as there are only two bulbs, stop/tail which also flashes as an indicator and reversing.
A little bit of jiggery pokery and the stop and tail work as standard, the reversing bulb is replaced with an orange one and this now acts as the indicator. The lower section of the light housing is clear and as the tail light is now at the bottom, this illuminates the rear number plate if put in the US location.
All very cool looking, except .... now I have no reversing lights and once the standard bumper is ditched for a Warn one, I will have no location for the fog light either ...