Mounting driving lights to the bumper can induce jiggling, depending on where they are mounted. The bumpers are fiberglass and not the most rugged thing you could mount to so they allow the light to vibrate slightly. A better solution might be a mount that clamps on to the bumper mount bars and holds the light securely. If you do a search on here you'll probably see a photo os someone's set-up. In the photos below showing my Nerf Bars, those mounts simply grasp the top and bottom of the bumper bracket and have a 90º tab at the top to mount the light to. They're pretty effective.
My car is more of an outlaw with Nerf Bars for bumpers, so I made up a pair of stainless steel brackets bolted directly to the body. Massive overkill, but they look decent and don't vibrate. The lights shown are Marchal 672/682 Driving light reproductions (non-fluted lens), are period-correct and are available from Beck or on eBay. There is also a fog light version (fluted lens either clear or amber) for the same money. If you go Marchal, make sure you get the H3 Halogen bulb version, NOT the Tungsten bulb, for better brightness. A good alternative is the Hella 500 (round) series, but the Hella lens is flat, rather than nippled. If all you want is decent light, either will do. Make sure you run a relay for the driving lights - the headlight switch can't handle the extra current.
