Sylvania's burned me too many times now so never again. Their 'Long Life' line of marker and taillight bulbs have proven to be garbage.
A quick inspection reveals that most of Sylvania's marker lamps are produced in third-world nations, and probably to an inferior quality standard. You are indeed correct: they are garbage.
One of the best options for marker lamps is a local Honda or Acura dealer. The Honda bulbs are made in the United States by Stanley Lighting, and are of excellent quality. They are pricey, but they are, in my opinion, worth the additional cost over the Sylvania/no-name bulbs.
Here is a brief cross-reference:http://www.candlepowerforums.com/vb/show...ley-light-bulbs