General Motors Compressor, Shaft Nut Missing

Most new GM compressors do NOT have a shaft nut.  TSB number 93-T-03, GM Corp reference 261204R and 111402R, dated October 1992:  Subject: "Compressor Shaft Nut Eliminated", all R4 and H6-series compressors.  The details are: "Effective after July 13, 1992 for the R4 compressor or April 28, 1991 for the HR compressor, the shaft nuts were/are no longer produced for these units.  This affects both production and service compressors.  The elimination of this nut has been made possible by improvements in the clutch driver to compressor shaft press fit.  If you receive an air conditioned vehicle with an R4 or HR compressor and there is no compressor shaft nut present, no attempt should be made to install a nut."