Yes, the quad headlights are smaller. They are 5-3/4" diameter. The inner and outer sheet metal is different due to the dual headlight buckets. I looked long and hard for a truck with them since they were only used on 1958 through 1960. All other years only had the single large headlight.
Thanks for sharing your journey. I am taking a similar one with a 58/78 C series. Question for you, what size are the headlights on your cab for the quad lights. I believe the single headlights were 7" but the quad lights look a bit smaller. I like the quad light look!
