WTK Headlight bulb Replacement

[Hitla]

Brothers, a lil help here please, i bought my first car on thursday, its a PCA AD wagon. I decided to upgrade the headlight bulbs and use the superwhite, i bought H4 which was recomended by the parts place, however when i try to install its not fitting up.. The original bulb itself is same but the metal part on the original bulb is shorter.. What type of bulb does this usually use??? any assistance will be gr8ly appreciated... thanks bro's.....

[cacasplat3]

the base of the original bulb should be stamped with the bulb type. check the bulb to see if it matches any of the common ones in the image below.
be careful with going to higher wattage bulbs, it can burn the harnesses (i know from experience)
also, i'm not sure, but i'll still say it, if its those bulbs with the blue coloured glass, don't bother, they are useless when it rains.

[ruffrider27]

H4B and the super white 100/90 w will burn out your original 3 pin socket .