My '57 has the flat back headlights with single post, sealed beam lamps. After browsing the archives and getting some ideas I made my own little mod to be able to use the 2 screw, 4511 sealed bulbs you can get at TSC for $8 (vice $36). Here it is if anybody is interested.
I had some styrene plastic laying around from modeling. I cut out some pieces to use as insulators and fill in the hole on the headlight casing.
I took the brass tab that slid over the base of the old bulb and clipped off part of it. I then soldered it to the headlight case, and soldered a ground wire to it. (You could skip this and just solder the ground wire straight to the casing, but I wanted to leave the little brass tab there for looks.)
I drilled a hole in the plastic and mounted an 8-32 screw to serve as the post for the hot wire (kinda like the post on the distributor). It has to be pretty close to the top of the original hole to clear the center of the 4511 bulb.
I used the dremel to trim a little off the tabs of the new bulb to make everything fit, and voila - works like a charm. Be careful not to break the little piece of glass in the center of the bulb. It breaks the seal and lets contaminated air in. Trust me, you won't like the result.
I'm sure I'm not the first one to do this, but I couldn't find much for details on how to do it, so I figured I'd make a post. It was easy and fun, and will look very close to original when cleaned up and painted. It can also use the same wire that's already on the tractor - it doesn't require any additional wire length.