Incomplete Vehicle Export - 3rd Country Rate

Cannot find code for ‘Incomplete Vehicle Conversion’

I take a 4x4 Hilux pick-up (double cab), engine less than 2500cc, diesel and transform into 6x6 Hilux.

The code for the 4x4 Hilux is easy, but what is the code for the conversion ?

The vehicle is incomplete, in that it is then sold to a Fire Engine Company to be made into Fire Engine.