4x4 part number

[ironlemon]

Ive searched and seached some more but cant seem to find the thread with the part number i need. Anyways the part is the black box thingy that is mounted with two bolts on the fender by the vaccume box. It controls the 4x4. Has the vaccume lines and electrical connection on it. I need a new one. It is the reason my front hubs are not unlocking. I took it off cleaned it out, it worked for a while now its failed again. Ford part number or aftermarket?