This is just one piece of a HUGE pie,
The George Lawrence holster that came with my Model 36 had the following codes...after much research:

Lawrence holster code:

24 = model # (this one had belt slide and snaps)
D = black
C = chamois liner
W = white weave edge (haven't seen one since)
X = left hand

540 = for S&W Model 36 2” barrel

p.s. Gave both the holster and Model 36 to my daughter-in-law. She got rid of her Ruger LC9 in favor of the Model 36!