2000 ford ranger 4x4 transfer case actuator

I picked up a used ranger. Guy says the transfer case actuator needs to be replaced and 4x4 will work. I order the actuator and climb under the vehicle to remove old one and install new one….. the old one isn’t there. Someone previously has removed it. Tried to slide new one on and it won’t slide on….. am I missing something here?? Why can’t I get this to slide on??

This truck has no power mirrors or locks…. So what fuses control the 4x4?

Thank you in advance