42. (1) No owner of a motor vehicle shall so alter the vehicle that the particulars contained in the certificate of registration are no longer accurate, unless:-(a) he has given ¹[notice in writing] to the registering authority within whose jurisdiction he resides, of the alteration he proposes to make, and(b) has obtained the approval of the registering authority to make such alteration:Provided that it shall not be necessary to obtain such approval for making any change in the unladen weight of motor vehicle consequent on the addition or removal of fittings or accessories if such change does not exceed two per cent of the weight entered in the certificate of registration. (2) No alteration which is likely to affect the chassis identification number, chassis construction or the make and model of the vehicle or the maximum limits in laden weight certified by the manufacturer shall be allowed. (3) Any change where class of vehicle is effected shall be treated as new registration and the provisions of section 33 and section 34 shall thereupon apply. (4) Where a registering authority has received notice under sub section (1), it shall obtain the opinion of the concerned Inspector of Motor Vehicles on the proposed alteration and shall within fourteen days of the receipt of the notice communicate (by registered post acknowledgement due) to the owner of the vehicle its approval to the proposed alteration or otherwise. ²[(5) Notwithstanding anything contained in sub-section (1), the authority may, by notification in the official Gazette, authorise, subject to such conditions as may be specified in the notification, the owner of more than one vehicle of the same make and specifications to alter any such vehicle so as to replace the engine thereof by an engine of same make and specifications without the approval of the registering authority.] (6) Where any alteration has been made in a motor vehicle with the approval of the registering authority or by reasons of any change in its engine number without such approval under sub section (5), the owner of the vehicle shall, within fourteen days of the making of the alteration, report the alteration to the registering authority within whose jurisdiction he resides and shall forward the certificate of registration to that authority together with the prescribed fee in order that particulars of the alteration may be entered therein. (7) A registering authority other than the original registering authority making any such entry shall communicate details of the entry to the original registering authority and to the authority which issued or last renewed the certificate of fitness.