I'd assume that the other 2 pins are for the power-folding function?
You CAN remove the electronics from your old mirrors and install them in the new ones.
- There's a disc on the back of the mirror housing - you can see it with the mirror cap off. Un-clip that - carefully.
- There's a cut-out segment on the underside of the mirror - that slides out.
- With the mirror not mounted to the car, carefully wedge a trim removal tool or such under that 5 pin connector and work it loose.
- There is then a clip on the plug that releases it from the housing.
- Disconnect the wires going to the heating element on the back of the Glass.
The wiring loom is now free so just pull it out. Do this for both mirrors and then install your old wiring loom in the ///M Mirrors.
PS: Take the Mirror caps off the mirrors while they are still on the car. MUCH easier to do then when they are off.