Niraj
i had same problem like u and procedure is as follow
first u need to fill up Form 107 which is supplementry deed for extention . if u are submittion these form after 60 days of completining ur articleship than u need to pay late filing charges by way of D.D. along with lettter{late pyt charges is mentioned in last page of Form 107} Also u required to get franking only this form and not any other form
second u need to fill up Form 108 for actual durataion that is for only 3 years
third for extra duration u worked ( i.e. in your case extra 5 months u worked) u need to fill another 108 for
5 month . where in u have to state no. of week served
Hope abve will be useful to You
Nd Yap have a independance life as u have completed ur articleship..!!!!!!!!!!!