The next part is pretty challenging. You will need a special tool to compress the spring that holds the mirror to the mount. I fabricated a tool myself by cutting a half-inch of 3/4 inch pipe. Then I cut two notches in one end. Using a bolt and washers I was able to compress the spring to remove the retaining clip.
Installing the new mirrors is almost the complete opposite.
Put the new mirror on the mount. Using the same tool, compress the spring and secure it with the retaining clip.
Thread the wiring harness through the back of the mount and up threw the center of the spring.
Then thread it through the hole that enters into the inside of the mirror housing. The picture shows the plug already reattached. However it was threaded before the plug was reattached.
Before you reattach the plug you set aside, check to see if the harness needs the wires lengthened. One of the sides does and the other does not. If it does, cut the wires and solder about 3 inches of wire for each of the 3 wires. Then reattach the plug using the marking for the Black, White and Red wires.
Attach the plug to the back of the motor. Then mount the motor to the mirror housing using the 3 long screws you removed earlier.
Attach the 2 brown wires to the back of the mirror glass. Then pop the glass back into the motor.
Repeat for the other side and you're done!