Hello,

So many possibilities. Something has lost a connection during heavy load, so it burned, was corroded, or loose. One common overlooked spot is the ground cable at the right motor mount. It goes around the rubber motor mount to complete the ground between the engine and frame. Remember when checking for power it may appear there is no power when you really have no ground where you connected the test light or meter ground. Another spot to check is the wiring harness bulkhead (firewall) connector. If you get a few more test results and details I can help more. Do the headlights light? etc.

I have a 73 that that  would only click the starter, it showed power at the starter, SOO a new battery, Nope same problem, next a new starter, same problem. Time to get serious, after much checking and taking the battery cables out I found a corroded place where the cable went through the body underneath and had worn a hole in the insulation, fiberglass body didn,t conduct so no sparks ect. I was getting enough power to work the low drain devices but not enough to power the starter. Check your cables. 

Check for battery voltage at the large cable on the starter. You have to have voltage there first. Be sure to check the ground, as Ken says. That chassis-to-engine ground causes a lot of electrical problems, and it's usually the last thing anyone checks. The ground system is as follows....from the battery, the ground cable goes thru the floor of the compartment, then directly to the chassis, under the seat area. Remove that cable, and clean the cable end, and the frame where the cable bolts on. From there, there is the ground cable from the frame to the engine, passenger side, and it bolts to one of the engine mount bolts. Clean both attachment points there. That should give you a good, solid ground for the car, and engine.
You should have battery voltage at the starter, as I said, and battery voltage on the large cable of the alternator.
You said you checked the fuse-links, but for resistance only. Those things can fool you like testing that. You need to check for voltage on both side of the link. Of course, you still need to have voltage at the starter to begin with. If everything on the car is dead, electrically(lights, horn, etc), you have either lost your voltage supply from the battery, or the ground. Happy hunting! Let us know what you find as you go.

Hey there, have you figured it out yet? I am having similar problems and have changed out the battery, starter, alt, ignition switch, nuetral safety sw, and horn relay...also checked continuity in battery cables and fuse-able links.? y

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|UPDATED|11/18/2015 10:45:57 AM (AZT)|/UPDATED|

No. really haven't even tried anything yet. I bought a totaled 71 Coupe with no engine or trans off Ebay. I am going to use this 79 for a doner to put the 71 back together. Some day I will have a lot of 1979 parts for sale, the engine and trans is going into my 1977 Z28 project I also have.  I don't know if I will even bother worrying about getting this 79 running, although it would be nice to drive it around the parking lot at least before dismantling it for parts. If anyone out there is looking for parts, this 1979 red on red L-48 auto is 99% completely original. I can send pics of any particular area of the car.. Thanks

Always always check the actual battery cables.  We spent all summer on our tractor, did the alternator, then the starter etc replaced all the battery cables except the one that connected the two batteries together in cycle.  Guess what the cable we didn't replace was no good.