Typically, when the mirror is accidentally driven into a tree branch or other car or object, either the mirror or the swivel bolt cracks, rendering the mirror useless. But it's worth hanging on to the extra parts, you can get the good mirror off and glue it onto an intact swivel frame.
The mirrors are glued with silicone to the inside black plastic frame. Trick is getting the good mirror off without cracking it.
When my mirror broke, the chrome back housing popped off the black plastic frame as well. If it had not, I don't know if I would have been able to remove it without bending - stretching - the metal, then it won't fit and could keep popping off.
I used the chrome back housing, inner black plastic frame, and swivel bolt from one unit - everything but the mirror.
I used just the mirror from the other unit, trashing the chrome back housing and inner black plastic frame to get the mirror off.
I have a collection of the chrome door brackets. That may become another instructable...
Step 1: Remove Chrome Back Housing From the Good Mirror
Using screwdrivers, carefully pry the chrome back off the plastic frame. I bent the chrome back and broke the edge of the plastic frame, but who cares - I only needed the mirror on this one. The chrome back housing is glued inside in four corners to the black plastic frame with silicone. There may also be double sided foam tape holding it in the middle. I ended up stretching the metal, so there is no reusing this part.
Be careful not to brake the mirror. One of the corners is probably looser and once you get that off, the others are easier. Careful not to cut your fingers on the sharp edge of the chrome back.
Step 2: Saw Off Parts of the Plastic Frame to Access Silicone Glued to Mirror
Using a hack saw, carefully saw off the four corners of the plastic frame to more easily access the silicone glued to the mirror. Saw both sides of each corner.
Do in a well ventilated area, the plastic dust is toxic. The hack saw blade will get super hot, don't burn yourself. I used foam meat trays to cushion the mirror and to catch the plastic dust. Leaned the mirror on a table outside, held with one hand, hacksaw in the other.
Didn't try a reciprocating saw (SawZall) - would have been much faster. Worried about the vibration breaking the mirror. First time you tend to be careful. The hacksaw took a while, I would try the SawZall. The plastic is a little soft and the mirror is well protected, so I don't expect it would break that easily. Be patient.
Step 3: Use Solvent to Pry Mirror From Plastic Frame
Now you can see behind the mirror and the points where it is glued with silicone to the black plastic frame, and access the adhered points.
Pour some solvent onto the back of the mirror around the silicone dots, to loosen the silicone. Use a paper towel soaked in solvent slid inside there, let it soak. Goo Gone, CitraSolve, or Mineral spirits will work.
Nothing really dissolves silicone, solvents only soften it.
Then use something plastic (an old credit card cut to size) that is thin, sharp, and sturdy enough to pry and cut the silicone loose. You don't want to use a knife or metal object that can scratch or even crack the mirror.
As you get some of the corners loose, GENTLY push the mirror down with your thumbs through the sawed out openings in the plastic frame. You can feel how tight the silicone bonds are, don't push too hard and break the mirror. Keep soaking in the solvent and scraping and/or cutting through with the credit card.
BE PATIENT AND DO NOT BRAKE THE MIRROR. Let the solvent soak in and work slowly. That silicone glues really tight!
I cut an old credit card to about 1.25 inches width to slide inside the cutouts in the plastic, cutting and scraping the silicone. Used a gentle scraping motion to cut through the silicone and pry it loose from the plastic.
Once the mirror is free, any silicone stuck to the back of the mirror can be scraped and cleaned off.
Step 4: Clean All Parts, Lubricate Swivel, and Reglue With Silicone
All parts to be re-glued must be clean and dry so that fresh silicone will adhere properly. The silicone sticks and is very hard to get off.
Soak the remaining silicone in solvent and scrape off. Use soap to wash the solvent off. Use alcohol or glass cleaner to clean the mirror. Use sand paper or steel wool to remove old silicone and any greasy residue from the plastic, if needed. I used Bon Ami to polish the inside of the chrome back housing.
The swivel bolt and springs can be cleaned and oiled with 3-in-1 oil or WD-40, while they are easily accessible. Re-attach the swivel bolt/springs with the 3 screws into the black plastic frame BEFORE gluing. Temporarily attach to the truck frame (torx or star bolt) and move the swivel around to lubricate and make sure parts are moving easily. Clean off any excess oil.
Make sure all the parts are all clean, grease-free and dry.
One more step before glue:
Make sure the chrome back housing clicks into the black plastic frame BEFORE applying glue. You might need to bend the chrome a bit. Careful of the very sharp edges! It was pretty tricky getting the housing back onto the black plastic frame - mine had snapped off when it was driven into a tree branch (and the mirror broken), so it was slightly bent and did not fit. I used a rolling motion, leaning the edges on a table top to bend the edges inward, and pliers to bend the extreme edges. The chrome edges need to click into the black plastic outer frame, into the outer groove - it will pop out easily if not seated. I used my hands to get one side in, 2 corners all the way in, then rolled the 3rd corner into place (you will hear a click when it seats), then the 4th, last corner was still sticking out. I had to use a small thin screwdriver, with a rolling motion shoving the chrome edge into the plastic groove, to nudge the last corner in, and pushing hard (but not denting the chrome) to get it into place.
Once I figured out how to get the chrome on, took a few cycles of putting it on - not quite all the way, pulling it off and bending the edges inwards, PRACTICING until I was sure how to get it on, THEN I applied the silicone glue to the black plastic frame and put the chrome back on one last time.
I used a clear exterior silicone adhesive that dries in 30 minutes, $5 tube, for windows and doors, etc.
Glue on the mirror: Apply the silicone to the front of the black plastic frame (as shown in photos) and press the clean mirror on.
Don't let idiots who drive into tree branches drive your truck anymore.