I am in the process of taking the pulley off to see if the compressor is gone or not.. Is there a special tool to get the square nut off under the cover?? I'm afriad if I use any kind of clamp i'll strip the metal due to all the 26 years of corrosion..

What A/C compressors can get swapped into a 280zx 1980?? I've looked around but can't find a 1980 model.

They use a Hitachi MJ167 compressor. Checker/Schucks/Kragen has them. I forget their number. The difference in the ZX compressors is the size of the flare on the low side port but that doesn't matter since the one's that Kragen sells don't come with the ports. You use the ones from your old compressor. If you get one from them, be sure to use new o rings.