Here's one I've got!
This a pic of a new one as it comes for a 126 chassis. It has a three conductor molex connector with a firewall grommet and two female spade connectors one on a red wire and the other on a blue wire. The aluminim part is a heat sink sometimes called a "porcupine", the electronic device is probably a transistor, SCR, or a triac of some sort.Three wire probably go to the semiconductor and the other two are probaly a thermo senseing device to prevent a meltdown, that may be the nature of your particular failure from the looks of it.
It appears that the semiconductor is controlled by the Automatic Climate Control unit (push button unit in the dash) which turns the switch on and off at various frequencies to control the motor speed using PWM (pulse width modulation) or something like it. The semiconductor in the black box mounted to the heat sink appears to have failed by the heat damage evident on the aluminum. You might want to consider having the ACC checked before connecting a new expensive part to it, it is probably unlikely that the control signal caused the failure but you never know burning up a new one would be a hard way to find out!
The best bet is probably a bone yard for a used one, get a couple they will ether work or not, good or bad, no in between. You might be able to open the black plastic and find out if the switch is an industry standard part and replace just that, might want to start a rebuilding service when you see the prices for a new replacement part!! Good Luck!