Did some early 72's come without the seat belt light. I have a 72 harness judging by the pinout on the bulkhead connector and it has the key minder buzzer and TCS relay connectors but no seat belt light, buzzer or seat belt connector.???

Cannot say for sure, but a lot of the safety stuff was legislated to be put in place not by model year, but by calendar year. So the light must go in on Jan 1 , 1972. I worked in the car industry from '69 to '79 and thought that the car companies really played games with this stuff to save pennies. And to make replacement parts a nightmare to properly choose.

ttt

Bought my 72 in October of 71. It came with the seat belt warning system but being a California car maybe it was ahead of the curve. By January of 72 it no longer functioned due to loose connectors.
Don't recall seeing a 72 Chevelle or Elky without the system.