I have fellow classmate that has a 79 ranchero w/351m, fmx trany, and power everything. He is looking for wiring diagrams to get back up and running again. He bought is as a project vehicle. But he's replacing the 351m with a 460. The 351m is froze up from sitting.

 

Try eBay Motors---they have many, many older factory manuals including wiring and vacuum books called EVTM for Electical & Vacuum Troubleshooting Manual.

I've bought a lot of nice manuals for cheap there! Use this link and select from the choices for your year and model: Manuals Literature | eBay




HTH