An often overlooked item when installing a T56 Magnum is the Reverse Lockout Module. Because of the location of reverse (next to 5th), it would be too easy to accidently hit reverse during a 4-5 up-shift. Not a good thing. To remedy this, Tremec built in a Reverse Lockout solenoid. In the off (de-energised) position this solenoid prevents the shift lever from entering the gate for reverse. Note: It can be over-ridden with a lot of force. When activated the solenoid opens the gate allowing the lever to move to the reverse position.
So people have come up with various solutions to activate this solenoid from switches mounted nearby to switches on the brake pedal.
The safe alternative is to monitor vehicle speed and only allow the reverse lockout to de-energize the solenoid at low vehicle speeds. This electronic module from Modern Driveline contains a microprocessor that constantly monitors the vehicle speed while you are driving. At low vehicle speeds, The reverse lockout solenoid is energized to allow you to shift into Reverse. At speeds above about 5 MPH (typical) the control module de-energizes the lockout solenoid, therby preventing inadvertent shifting into reverse at higher speeds.