Will this glass drop straight into my existing mirror housing?

Yes. This lens mounts at factory points—no drilling, no brackets, no adapters needed. Your current mirror frame accepts it as-is.

Do I need to remove the entire mirror assembly from the truck?

Not necessarily. Depending on your truck's design, you may be able to access the glass from behind the housing without pulling the whole mirror. Test-fit first to confirm your removal path.

What if the glass doesn't hold in place after I install it?

Mounting method isn't specified in the product data—inspect your factory housing clips and backing mechanism before installation. If clips are bent or missing, replace them first so the new glass seats properly.