The clock for a 1966 truck is an accessory that you could purchase at a GM dealership.
It is a universal clock that mounts on top of the dash and was also used on cars.
Today the clock and housing are rare and overly expensive.
Do you have the original housing?
If not, save your money and buy a clock with a magnetic base for you dash.
https://www.ebay.com/itm/203447267462
