My 89 F-250's wire harness is a mess. Previous owners have messed with the harness a lot.Cutting cords and wiring stuff where it don't belong. It was originally an automatic C6 then converted to ZF 5S-42 manual. Dash cluster dose not work. Front light wont work. Break lights wont work. So my main question is would a wire harness from my 88 Thunderbird 302 fit and work with my 351w truck? Would it fix those problems? I am planning to switch the manual transmission to the AOD in the 88 Thunderbird. That should help with the wire harness connecting?

 

Can I post pictures? If so then how? I can show my wire harness nightmare. And it would help narrowing down certain thing.

 

Anything is possible but you will wind up hacking the thunderbird harness as bad as your current mess. There are literally thousands of the trucks in salvage. Go to a pick and pull and fined one that the hasn't been molested and pull it and start over.

 

Where can I find a complete wiring diagram for the 89 f series?

 

What you want is called the Electrical and Vacuum Troubleshooting Manual or EVTM. Only the Ford document is worthwhile. No point in Chilton's or Haynes. Every year has it's own manual, but I think 88 to 91 are pretty similar. Check on Ebay. Free online downloads are usually pretty disappointing.

And no, your 88 Thunderbird harness will not work in your Ford truck.