* New Grille: While the overall shape remained similar, the grille's details were subtly refined. Some sources note slightly altered horizontal bars or a change in the emblem placement.
* Taillights: Minor changes to the taillight lenses or bezels might have occurred, although these were subtle and often only noticeable upon close comparison to a 1965 model.
* Interior Trim: Variations in interior materials, upholstery patterns, and dash accents might have been implemented across different trim levels, but these weren't broad, sweeping changes. Think subtle color palette shifts or minor changes in fabric weave.
* Wheel Covers/Hubcaps: Design variations or options for hubcaps were possible, leading to subtle aesthetic differences between individual 1966 Mustangs.
* Badging: Slight alterations to emblem placement or font style on various badging could have occurred.
It's important to note that pinpointing *every* minor change requires examining detailed production records and comparing many individual vehicles. Many of these alterations were incremental and not widely publicized. The major changes (like the fastback addition in '65) were far more significant than anything implemented for the '66 model year.
