Section 153(1) in The West Bengal Motor Vehicles Rules, 1989
(1)If the holder of a permit to a particular vehicle by specification of the registration mark desires at any time to replace the vehicle with another, he shall forward Part A of the permit and apply in writing to the Transport Authority by which the permit was issued stating the reason why the replacement is required and shall-(i)if the new vehicle is in his possession, forward the certificate of registration thereof: or(ii)if the new vehicle is not in his possession, state any material particulars in respect of which the new vehicle will differ from the old.
