I've got genuine Volvo/Cibie/Valeo-branded headlights and park/turn lamps on my '93 240. I got them from overseas (daughter took business trip, and bought them for my birthday present).

The parking/turn lamps fasten to the headlights' housings by being slid into a molded plastic channel (kind of like a dove-tail joint that a carpenter would fabricate in some furniture); they're securely held by another molded, springy piece of plastic on the headlight housing that firmly snaps into place to block the lamp from sliding out of the channel.

There's no metal clips, as you show in your illustration, anywhere in the installation.

You might be thinking of pre-'86 cars, and their e-code (sealed beam substitute) headlights. But the guy is talking about his '90.