Whats this box?

I have inherited a 88 XJ Laredo with the 4.0 auto 4x4. As I was going through to see what it needed, I came across a Yellow box that is mounted to the lower dash panel. (under the steering column). It has AMC on the top and 3 differant adjustment points on it. One I think was "centerline". Any idea what that box is. Also the trans has a "Power" and "Comfort" switch that doesn't seem to work, no relay sound or light. Is that just the Overdrive lock out, or something else. Thanks in advance.

That's the cruise control module.

As for the switch, there should be a small yellow light built into the rocker that lights in "Power". It may be out. But the switch changes the shift points in the transmission. In Comfort, the shift points are a bit lower and and it takes more throttle to drop back down a gear. I assume by "comfort" they mean it doesn't shift as much. In Power mode, the shifting is more aggressive and mine downshifts much quicker when climbing hills or carrying a big load.

With the switch in Comfort, try gently accelerating (no burning rubber) and note when it shifts. Then hold about 50mph and press the gas pedal, not quite to the floor but close and see when and if it downshifts. Then try the same in Power.

Thanks Saudade, Yes the "Power" switch does have the yellow indicator, but it doesn't light. Once I get the motor/tranny mounts replaced, I'll take it out and see whats up. I noticed that there is a place in the fuse panel that says TRANS, I assune that this is transmission, I put a fuse in there but there still was no light on the switch. Any other ideas. Also, it has a Dana rear, is it a dana 44? Did that rear end come as a limited slip or just the standard open? Ok, one more question, does anyone have the schematics for the power windows, I have the DS and the PS Rear door windows working. Thanks again for the timely responce Saudade.