When my friend Jeffrey came over from the Netherlands for the Vintage, he brought me a pair of euro flat style turn signal assemblies. Since they only have single element bulbs in them, they need to be modified to accept two element bulbs. Since this comes up from time to time I thought I would show how I did it today, using some $4 bulb holders from Advanced Auto Remove the single element electrical connection which pops right off, remove the reflector and enlarge the hole with a Dremel tool, do the same with the original hole that held the bulb, large enough for the new socket to fit in, drill a couple of holes to hold it all together with some small machine screws (using the retainer plate provided with the sockets) and voila, it can now be put on a US spec car. A couple of hours is all it took for both sides
HTH
Faithful dog Molly keeping watch