Paul I have a 1986 XLT, 5.0Ltr. FI unit
I have not found any appreciable difference in the "85-"86 model with the possible exception of some exterior trim, front grill, and sometimes the high mounted "stopping" lamp. There were no significant differences going back to 1984 when Ford introduced the AOD overdrive transmission to these series trucks. I also believe that was also the introduction date for the 5.0Ltr FI engine to this series truck also.
I have successfully used the easily available Haynes book when rebuilding my unit. I have found from much usage that it is reasonably the most accurate manual for most common service work for that truck; with the exception of a Ford Service manual.
The electrical schematics, and diagrams are pretty much what you will expect in the truck. There were some production variables within any vehicle run, but most noticeable variables were listed in the Haynes, Ford F-150,250,350, Bronco Book.