Are wanting a "schematic" (wiring diagram) ? or a diagram of the fuse box? (Your question is a little confusing) If you are wanting a diagram of the fuse box, all I can say is "good luck". Those were not even available back in 1979...you'll really have trouble finding one 32 years later! The fuse box should be marked which fuse is which anyway...that's the way they did it back then.
On the other hand, if you are looking for a wiring diagram, you can possibly find one if you contact the sales department at AllData.com
Their DIY information available online only goes back to 1982. Howerver, they also have "vintage model support"
for professional AllData subscribers. I have gotten wiring diagrams from them in the past dating all the way back to the 1960's. You might check with them to see if there is a way they can get you the information you need without having to sign up with a professional contract.
Please post a comment to let me know how this goes so I know how to advise future requests like yours. (I see similar requests on this site regularly.)