I replaced them on my '73 about 4 months ago. I just jacked up one side at a time. Aside from the obvious things to disconnect like the steering coupler I also removed the front frame extensions and the two extreme corner braces for the rear bumper, also had to remove the rear bumper on mine. Your 79 obviously doesn't have a chrome bumper but I'd bet the brace is there in some form. I didn't disconnect the emergency brake cable, the brake lines, any ground straps or wiring. Watch your fuel lines in RR corner.
When I lifted mine I placed some 2x4 blocking under the floor pan to distribute the load from the floor jack and just jacked it up. I was able to lift it about 3" - 4" on each side. It went up really easy and the mounts were easy to get to then. If I had to do it again on my car it would probably only take about one afternoon.
If the nut above the rear wheel well spins inside the square cage just squeeze it a bit with a pair of vise grips. Thats what i had to do.
good luck
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