11:th-Feb-2016, 20:15:39
It seems upon me investigating further after calling at Vauxhall today , the gtc is a 9012 bulb. Halfords and other auto shops don't have any. Luckily Vauxhall had one in stock. At a ridiculous £30 including vat . Thought I will buy one to keep as a spare and try matching another bulb to it. Don't want to go down the hid route for several reasons. It seems a hb4 9006 will fit if I modify one of the lugs. Unless anybody else has found a good white 9012 halogen bulb . Pics of standard bulb to follow