It was either an extremely common (like 99%) option, or it was a standard item that could be deleted. One of my friends in college had a plain-jane bottom of the line 93 that didn't have it either.
A more familiar example might be the F-150. The base package, or the "standard equipment" would be regular cab, 3.7L V6, 2wd, manual windows and locks, with steel wheels.
How many do you actually see in that configuration? I have seen one is the last 4 years.