Compressor Clutch Removal

[kharrell]

I'm attempting to remove the clutch pulley on a Harrison A/C compressor that was removed from a late 80's GM vehicle. I removed the shaft nut at the center of the clutch pulley and attempted to use a puller to remove it, it wont budge. Am I missing something? Like maybe a hidden snap-ring? I would appreciate any help or advise.

Thanks