DVLA uses a points system to decide what registration number to give a radically altered vehicle.
To keep the original registration number.
Your vehicle must have 8 or more points from the table below if you want to keep the original registration number. 5 of these points must come from having the original or new and unmodified chassis, monocoque bodyshell or frame
Chassis, monocoque bodyshell (body and chassis as one unit) or frame – original or new and unmodified (direct from manufacturer)
Suspension (front and back) – original
Axles (both) – original
Transmission – original
Steering assembly – original
Engine – original
Get a ‘Q’ registration number
You won’t be able to keep your vehicle’s original registration number if one of the following applies:
it has fewer than 8 points
it has a second-hand or altered chassis, monocoque bodyshell or frame
there’s evidence that 2 vehicles have been welded together to form one (ie ‘cut and shut’)
Your vehicle must pass the relevant type approval test to get a ‘Q’ prefix registration number.