Miscellaneous elements of ES-335 Construction
The first picture shows the bridge pickup cavity. You can also see the ABR-1 bridge. The earlier examples of the ABR-1, as shown, do not have a retaining wire to hold the bridge saddles in place. Later, a retaining wire was added.
The small blocks on the underside of the pickguard vary in shape as well. In the photo, the guard on the left is from 1959 and the smaller block on the right is from 1964.
The last photo shows a 1959 and a 1963 335 side by side to reveal the difference in thickness. I have taken many measurements of a lot of 335, some of which can be seen on the Weights & Measures page. The guitars varied quite a bit, and I have found very few that actually meet the original specification of 1.75".