CBS TV strike poster sign picket line used 1972 ? Recording Engineers vintage LA

Doing some research, this could be from the 1972 CBS strike. It could also be from one of the strikes in the 1960s (potentially 1967). I bought a bunch of 1960s ephemera at an estate sale. The man whose estate it was worked for CBS TV in a set/behind the scenes capacity, his granddaughter told me. Other than wiping off the cobwebs, the sign is in original condition - stains, tape, staples. Shipped flat. Posterboard/cardboard. Two single sided signs put together.