67 CST's do exist though they are quite rare. In 67 the CST package also included bucket seats. In 68 and later bucket seats were a seperate option from the CST package.
The Custom package was a trim level under the CST package. It carried through the 67-72 years.
You could option Custom trucks with carpet, bucket seats chrome bumper and such so it would apprear pretty close to a CST without actually being a CST.
