I spent a long time trying to find a definitive Mary swap thread I did mine last night and I thought I would create one unfortunately I didn't take pictures but it was super easy if you know what you're doing.

I got mi r53 mirror on eBay for 30

I swapped an r53 mirror into my r56 remove the electronics from my r56 mirror and tucked it up into the headliner it works perfectly. This is the best removal instructions
Pelican parts directions

Tools Needed

• small screwdriver
• small side cutter
• Pliers
• guitar pick phone opener type tool

First remove your mirror from there are 56

• separate the trim on the pedestal mount with a small screwdriver so you can access the plug to the electronics.
• Unplug
• Twist base 90 degrees

The mirror will come down

• Now take your fingers and push the plug into the hole and to the left side of the car
• Gently pull the headliner down and pull the plug out towards the front of the car.

Taking your mirror apart is not hard but may be destructive. Like taking apart a cell phone

• Work a small screwdriver or guitar pick type tool around the seam where the trim hold the glass in.

Next part is hardest. You will see the circuit board. Part of it runs along the bottom of the mirror part up the back on the right side. The part on the back looks like the antenna to me.
The board is held on by 2 screws that cannot be accessed in some kind of non destructive manner.
One person suggested drilling access holes for a philips screwdriver

• I used a very small side cutter to cut the part of the plastic the screws screw into above the board.

On the left side access is easy. On the right side I have to come in from the top and get behind the antenna. A bit tricky.

• Now gently pry the day night **** off of the bottom of the mirror. With the small screwdriver You might not break it.
• Now use pliers to remove the clear post. You might not break it.

I broke one of these two parts the **** would reconnect to the postThe board is now free from the mirror except for wiring

• Unplug the white plug at the board

One person suggested depinning the plug to remove it.... Don't do that

• Turn the white plug so you can push the narrow part through the hole in the back of the Mirror
• Now poke it through with a screw driver gently. Maybe you could pull it out but I think pushing it is safer.

the board is now free.Install your r53 mirror.

• Turned 90 degrees push the base up to the clip and turn it 90 degrees untill it faces you

Now the board

• Cover the board in electrical tape. You might try to flatten the board or resolder the antenna and reconnecting it with wires to make a flatter package. I thought about it but did not. I may take it down and redo this part..
• now plug it in.
• Test your key remote.it still works.
• Now push it up into the headliner from the front. Now you see why flattening would be easier. It will fit though

Enjoy your small mirrorIt will seem really small for the first day then you won't even notice that it's small you'll just enjoy the view

Because I was mostly careful I was able to put my old mirror back together I put the clear post back up into the day night mechanism that worked fine I tried to attach the **** back to the bottom of the clear post that did not work I put the glass back in and clipped the mirror frame back to the Mirror like putting a phone back on that worked fine and then I pushed the pedestal trim back together that worked fine so now my old mirror could work well if I could figure out how to get the **** back on and get day night again , epoxy maybe otherwise I could pull the post back out and not have day night
Enjoy