Will this fit my factory towing mirror housing?

Yes, this lens mounts directly into the OEM mirror bracket using factory mounting points — no drilling or adapter plates needed.

Do I need both left and right lenses at the same time?

Not necessarily — you can replace one side. Order this right-side lens, or grab the left-side version if you need to refresh both mirrors.

What condition is the lens in when it arrives?

Glass lens only — it arrives ready to install into your existing mirror assembly. No adhesive or sealant included; install per your mirror's factory design.