1996 Chevy Suburban 4X4 actuator

Drive Train Axles Bearings problem
1996 Chevy Suburban V8 Four Wheel Drive Automatic

on the front diff the actuator that screws into the diff housing there are several types but what im after is an answer that will help with a project. Ive got a 99 suburban with auto 4x4 and the t-case got destroyed so I have a 96 with a manual shift and I need to be able to actuate the front when I shift the t-case, the 99 act, is a 5 pin and uses a limiter but is 250.00 the old style is 90.00 but is only a 2 wire unit and I tried a new one and it seemed as if you apply 12 volts to the unit and it pushes the plunger outward to engage the 4x4 but heres the problem. The unit has 2 wires and if you put 12 volts to the unit it slowly moves outward but it will apply the 4x4 but if you keep 12 volts to the unit it seems as though the unit gets hot and stays hot and it takes a while for it to cool down so that the plunger will release so now im wondering if gm kept 12 volts applied to the unit if so could mine be shorted or is it normal? Its working like a thermostat. By the way if you swap the wires it still heats up and pushes the plunger outward.