Toyota factory E-Locker with 4.56 gears.  The differential was re-geared with Yukon 5.29 gears.

Following information credit given to & written by: Hoaiphong Truong

Disabling ECU Safeties:

The locker ECU comes with two built-in safeties. One safety requires you to be traveling below 5mph for the locker to engage (once engaged, there is no speed limit). The second safety requires you to be in 4LO. To disable the 4LO safety, you have to cut the '4WD' line, which is pin #8 (blue/red) on the ECU, and ground it. The locker will now work in 2HI, 4HI, and 4LO. To disable the 5mph safety, you do the same thing, but with the 'SPD' line, which is pin #10 (green/orange). I chose to disable the 4LO safety while leaving the 5mph safety intact. Refer to the previous diagrams for pin locations.

Additional info by Steve Schaefer:

All you have to do to disable the 4LO requirement is cut a brand new 6" section of wire with a round screw eye connector at one end and a solder less wire tap at the other. Tap the wire pin #8 (blue/red) and ground the other end to one of the screws behind the drivers side kick panel. You don't have to "cut" the blue/red wire. If you want to return the truck to the stock manner of operation remove the solder less easy tap and your back to stock. Blue/red wire is still intact and not cut. I left the 5mph safety intact as I felt this was a good feature to retain.