Hi y'all,
I've recently run into a trash can and my driver side mirror fell out. The white backing is attached to the motor and I've bought a piece of glass that fits from Ebay, however, there's no backing on the glass to connect it back into the casing and onto the motor.

My local Honda dealership can order the glass which they THINK has the backing on it, but cannot confirm.
Rock auto doesn't have the part, though they have the right side mirror, and neither does Autozone or Oreilly.
Obviously mirrors are breakable and this is something that happens, so I'm confused as to why I can't find this part for my 4 year old vehicle.

Does anyone have experience here and can offer some assistance?

Thanks in advance!!