Your bulbs are the wrong fitting for the lights, but they are available to fit. JK think your light is up to 73 and your bulb is 73 on.
^ this. Your headlamps take the old R410 fitting for tungsten bulbs. You used to be able to buy H4 bulbs with an R410 base. Or you can buy these adapters https://www.ebay.co.uk/itm/18255029...ZKe2nuVQba&var=&widget_ver=artemis&media=COPY
JK sell both types, I used buy them off the peg at Halfords or any other motor spares type place, no need for adapters?
These adapters are not allowed in Germany - because the bulbs and adapters did not really fit to the optical path of an old Bilux headlamp - yes, you get light, but it is different to a H4 headlamp with H4 lamp. There are more small differences in positions with ugly side effects.
I’d did have the originals but my bus is a lefty so the beam was wrong for the uk I bought some rhd ones of here but it turns out they are for an earlier bus.
They will fit but I’ll have to run h4 conversion bulbs or adaptors. I could always use this as an excuse to fit some full led headlamps
The round base bulbs are designated P45t and the 3 prong bases are P43t which I'm sure both types are still widely available including uprated variants ie Osram nightbreaker.
I’ve got the ssp crystals in my bug. Really cheap in a sale years ago. Like about £30. I didn’t expect them to last but they still look new. That’s using car daily through the winter as well.