Basically, don't. At best you'll be downgrading(and you'll be very fortunate to only be doing this), at worst you'll become a dangerous menace to yourself and other drivers.

This covers LEDs as well:

https://www.danielsternlighting.com/tech/bulbs/Hid/conversions/conversions.html

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap