Wierd computer/module plug found under dash.

ok. i bought a 1999 (94-98 body style) gmc sierra 4x4 1/2 ton 5.7 truck a few months back. i just now noticed a wierd computer module looking box under dash. its right above gas pedal across from the ob 2 plug in. it looks just like a blank box with wires coming off it but a chip unplugs from it and a red light blinks when unplugged. some of the wires off it splice into some wires under dash and some go into a potter and brumfield relay. i guess just need to know what it could be. programmer or something else?. no ideas here.

Theft alarm? Not factory.