Mark86, The DRLs DO NOT need the light sensor. You can tell from the outside, if you have it or not. From outside the truck, look down at the front of the dash, near the driver's side. There is a spot for two sensors there. The first one (the closer of the two to the driver's door) is the solar sensor. The other one is the light sensor, the one we care about. The dummy light sensor has a concave (caved inwards toward dash) top. The real light sensor is convex and looks similar to the solar sensor.

Assuming you have it (and you probably DO NOT), then you only need to upgrade to the Limited dimmer switch. Just remove the steering column trim (3 screws) and then your current dimmer switch (2 more screws and 1 wire connector).