As you probably know, lens coloration of turn signals and taillights differed based on the part of the world a Porsche 911 was delivered to in accordance with regulations. Cars delivered to the United States had solid amber turn signals and solid red taillights interrupted by a patch of white for the backup lights. Cars delivered to the rest of the world (RoW, often referred to as Euro) had amber/white turn signal lenses and red/white/amber taillights.
Many prefer the more colorful Euro lenses and simply swap them for the U.S.lenses. That's OK but the housings and bulb mounting pattern is different between the Euro and U.S. lamps.
Dual 21/5w Bulbs
The dual bulbs are mounted behind the amber portion of the lenses, located in the same place on Euro and U.S. turn signals, so we're good there.
4w City Light Bulbs
The 4w city lights were mounted on opposite ends of the Euro vs. the U.S. housings. The Euro version version mounted the bulbs behind the clear area of the lenses, to the medial side of the housing, close to the horn grilles. The U.S. version mounted them on the lateral side where they could also be seen from the side of the car. To accommodate this, the Euro version housings mounted a small bracket to serve as the bulb holders on the medial end of the housing.