dvla help

hi ive got a 3.9 p38 engine i want to put in a different vehicle,
but when i informed the dvla i got a letter back asking for written confirmation from the manufacturer showing engine number and size,
cant anyone give me some advise on how to pursue this.
thanks

phone them up and explain it is a diy engine conversion not a factory fitment

Doesn't matter what you tell em, they'll still get it wrong.

With no help from me, my RR 4.6 HSE has this year miraculously transformed itself into a Range Rover LE Auto, which has proved interesting now I'm trying to renew my insurance (interesting as there is no such model for 98).

Same thing happened to my Vectra a few years ago - it suddently changed from a manual to an auto. Do they just let the students run wild in the computer records or something?