This is referred to as the "K5" relay in the 1968 Ford service manual. (In 1967 it was called the K7). This relay causes the flashing action of the 1968 Mercury Cougar instrument panel indicator lights and almost never works... The number stamped on this relay is C8WB-13A366-A or C8WB-13A366-C, the Ford part number is C8WY-13A366-A or C8WY-13A366-C.
We suggest replacing this unit with our new and improved solid state unit.
*Caution - Do not use the 1967 relay in place of the 1968 relay, smoke and fireworks will be the result.