This is referred to as the "K7" relay in the Ford service manual. This relay causes the flashing action of the 1967 Mercury Cougar instrument panel indicator lights. The number stamped on this relay is C7WB-13A366-A, the Ford part number is C7WY-13A366-C.
A quick bench testing: There needs to be continuity between the 'H' post
NOS item, new old stock.
*CAUTION* The 1967 and 1968 K7 relay look similar, but are not the same. Damage to your wiring system will occur with the wrong relay.
*NOTE* Need help diagnosing a Cougar turn signal problem? Victor Yarberry is the world’s most knowledgeable expert on the subject. Vic has owned Cougars since the 1970's and is the designer of all of our solid state sequential systems. There is no question he cannot answer! Here is a link to a great source of information on the subject.