Now as I was packing the old lamps into a box I happened to look at one of the old bulbs and it read 400watt !! Uh oh, that's right, 400watt. That's when I learned there is such a thing as a reduced envelope lamp.
I have seen fixtures that were factory marked with one wattage and had ben retrofitted to a different wattage. That's when experience can help out. A lot of times you can't read the markings on old ballasts.
They do seem to come up with a couple new types of lamps every year. The latest oddball I saw was a little bi pin metal halide. Dumb.