On Sunday I replaced the headlamps in my 83 300sd with some good Bosch
H4 units. I'm ashamed to admit that my Merc had cheap n' cheerful generic auto parts store sealed beams installed with awful light patterns.

All went well with the job apart with some minor difficulty with the retaining ring that holds the lamps in place - the short Philips screws that hold the ring in place just wouldn't hold and I had to use longer screws in a couple of spots. My guess is that the metal clip into which the screws mount was too corroded.

Has anyone replaced the fasteners with new ones or used nylon fittings instead? I am worried about corrosion over the longer term and you need to remove the retaining rings to change the bulbs each time.