I'm currently parting out an 89 F250 4X4. I'm saving all the cruse control components in order to fix the cruse on my 91 F250. I've got the servo and the steering column out. I know the amplifier is behind the dash. My question, is the cruse control amplifier the little white box next to the ECM (E9EB-10D840-AA) or the slightly larger black box next to the ECM (E9TA-9D843-DA)?
Just did a google search for the #'s you listed. Can't guarantee what the second one is, but from what I can find the first E9EB-10D840-AA is a chime control for seatbelts, lights on, door open, whatever, not cruise control. Not familiar enough with that era truck to know more but hope this helps a little.