I actually put LED bulbs in my old truck a few months ago. I was a bit worried at first because, you know, it's an old vehicle and I didn't want to mess up the wiring or anything. But the old bulbs were so dim, driving at night felt kinda risky.
So, I bought these LED bulbs online, and it turned out to be a pretty easy swap. Didn't need any fancy stuff, they just fit right in where the old bulbs were. The difference was huge, especially on darker roads. They're way brighter and don't use as much power, which is great for an old electrical system like in my truck.
I learned a lot about LEDs from this site, https://leds.to/. They had good info that helped me choose the right bulbs. Might be worth checking out for your LaSalle.