Guess your asking about the front seat belts and not the rear ones. Correct?
Would be helpful in the future to know what car or period of time your focusing on since there can always be running changes during a production year
But can report that no washers were typically installed between the seat belt anchor and the carpet - visible once everything thing was installed
One picture is available in the Unrestored Picture section of the site. Try:
Unrestored - Early 66 Shelby Picture Thread - Picture I1 in Reply #1
A few other examples
