Larkspur - of 3 or so 60-66 trucks I've owned, and a lot more I've 'known', they've all had mats that were full width - all mats after 60 were tucked under the sills - what makes you so sure your split mats are standard factory original?
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics