Admitteedly it was about 10 years ago that I bougth
them but I had no
problems getting 6V car bulbs then. I suspect they are still made if you
hunt
around.
Indeed, I had no trouble locating some here:
http://www.autobulbsdirect.co.uk/, including bulb holders too (I didn't
realise you could get generic bulb holders, I thought they would be specific
to each car and so quite expensive, thankfully this is not the case).
Regards
Rob