Now there is something I never knew about the lightning at all, but it makes sense, since the mustang for that year was the pace car as well. Was your dealer an SVT dealer? I found a picture of one on ebay tonight, and compared it to the cobra pace decals, and they are not even close. I can't even find any info anywhere on the net about pace trucks, never mind the 94 lightning, and 79 F-150, 250. If you come across something, let me know.
Other than that, if you had a really good picture, you should be able to take it in to a decal shop, and they can make it for you. Might cost a bit more, but it would be worth it.
Did ford even make these trucks public?

Les