Weird bulbs needed - HELP

[towncrier]

Hi Folks,
I have recently changed the Rear light clusters on my SR and I have need for a specialist bulb.
The bulb is for the rear fog light.......???? ..... I purchased some light clusters (ebay) and they are great, the only problem being they have 2 reversing lights (Clear bulb) and no rear fog light. I know all I have to do is change the offside clear bulb for a red bulb, connect the original fog light wiring and problem solved. NOT THAT EASY. It is a Lexus cluster and I cannot get a red bulb that fits.... it is the same as a 501 but is about 4 times as big...
It has also been suggested I colour the white bulb red (stops the correct amount of brightness, too dim).

Lets see how good we are, can you give me any help???? Please????