On AOD's the transmissions are mechanical. (AODE's are computer controlled.) Having the speedometer sensor connected or disconnected will make no difference on shifting or OD. The speedometer wiring only manages speed and mileage, hence why you have to change the internal gear when changing rear gears if you want accurate readings.
what exactly are the wires for? do they engage the over drive, and if so can i just put a switch in somewere in the car to turn the o.d. on and off? any advice?
The only wires on an AOD are for the neutral safety and back up lights. Shifts are controlled by a TV cable that is hooked up to the carb (similar to a kickdown). Unlike a c4/c6 which you can drive without the kickdown, if you attempt to drive an AOD without a TV cable, or with a poorly adjusted TV cable the transmission will burn out almost immediately and need to be completely rebuilt.
If you have an AODE you will need to get a Bauhman controller for it.
AODs have a shift pattern that takes getting used to.
D = 1 ,2 ,3 and OD gears
2 = 1, 2, and 3 gears
1 = 1
To manually shift it you start in 1, take it up to the RPM you want then shift it to 2 and then immediately pull it back on the shifter to 1. This will shift it into 2nd and allow you to hold that gear to your desired RPM and then shift it into 2 again and it will shift into 3rd.