Those are antenna trimmer adjustment instructions,used from 1968-73 for AM radios <u>only</u> Jeff.
They were removed from the radio,once the radio became part of the vehicle,trucks included..I've yet to see/hear any radio that was delivered with them still attached,as they hindered the buttons function,and had no use to the owner.
They told the prep tech how to trim the antenna during installation,prior to delivery.
----------ANTENNA TRIMMER ADJUSTMENT-------------
1)Tune to weak station or noise around 1400kc.
2)Remove right hand tuning and dummy knobs.
3)Adjust trimmer screw for max output.
4)Replace knobs and REMOVE THIS TAG.
5)Remove excess glue from pushbuttons with alcohol only.CAUTION
O NOT USE LACQUER THINNER.
They measure 2-3/4" X 3/4" w/red type.
Hamptons was reproducing these,when they were in business in the 1980's.I heard Osborn was afterwards.