Jerry Heasley
September 24, 2018

How can you tell the difference between a ’65 and ’66 Mustang? It’s not easy, since Ford used the same body in both years, but there are some subtle differences between the years. Here’s how to appear smarter about Mustangs the next time you’re walking around a car show.

Ford wanted to make the 1966 Mustang look fresh, so it offered styling tweaks, such as new simulated air intake scoops on the rear quarter-panels, a new fuel filler cap, and then the big bang in the middle of the ’65 model year—the GT package, which came out at the same time as their luxury interior with the famous Pony seats.

Key styling changes differentiate a ’65 from a ’66, with mid-year upgrades in ’65 adding complexity. We’ve outlined key changes below to form a Spotter’s Guide.

Standard 1965 Mustangs came with no hood lip molding and bright horizontal grille bars attached in a star pattern to a Mustang ornament in the center of a honeycomb-type grille.
Standard 1966 Mustangs came with a bright hood lip molding and a bright-metal Mustang ornament in a metal frame that appears to float in the center of an extruded aluminum grille made up of bright horizontal bars.
1965 and 1966 Mustangs with the GT Equipment Group incorporated foglights in the horizontal grille bar, plus a bright hood lip molding. The background of the grilles, however, is still honeycomb for 1965, with horizontal bars for 1966, as seen here.
The honeycomb grille background is unique to a 1965 Mustang.
Note the star pattern around the Mustang horse and corral, another key feature for 1965.
Ford added a standard bright molding to the leading edge of the hood for every 1966 Mustang.
The Mustang horse and corral was back for 1966, but without the large grille bars.
Standard 1965 Mustangs came with a unique gas cap and no backup lamps, which was a $10.47 option.
Backup lamps became standard in 1966 and Mustang had a new gas cap. Also visible are extruded aluminum rocker panels, standard this year on all three body styles (standard on the fastback only in 1965), and a new simulated rear quarter-panel sidescoop.
The 1965 gas cap was unique for 1965 Mustangs, both standard and GT.
The standard 1966 Mustang gas cap features a brushed finish in the center and a raised Mustang emblem.
The GT was popular and got its own unique gas cap for 1966.
Federal regulations mandated backup lamps for the ’66 model year.
The side of this 1965 convertible shows standard ’65 wheel covers and the ’65 rear quarter-scoop ornament.
This rear-quarter ornament simulated sidescoop is standard for every ’65 model, except the GT.
Ford added “three forward thrusting bars” to the simulated sidescoops for 1966. As in 1965, these scoops were deleted on the GT.
Styled Steel wheels had one change for 1966: trim rings, as seen here, instead of chrome rims. Fastbacks came standard with rocker covers in 1965, deleted on the GT, seen here.
In 1965, Ford’s Rally-Pac was an optional accessory, featuring a black wrinkle paint finish. The sweep-style instrument cluster was standard.
These full wheel covers were standard for all Mustangs in 1965.
The standard 1966 model wheel cover looks exactly like this, minus the spinner, which was a popular upgrade.
On close inspection, this car has the Accent Paint Option, a thin pinstripe running along the body-side sculpting lines that deleted the rear quarter-panel side-scoop.
Accent Paint Option, a thin pinstripe running along the body-side.
Introduced midway through the ’65 model year and available for hardtop, convertible, and fastback through 1969 was the GT Equipment Group, with GT stripes and ornament visible from the side on both ’65 and ’66 model years.
When Ford introduced the GT for 1965, they also introduced the Interior Decor Group, which included the following features: luxury bolstered seats and door panels, padded sunvisors, woodgrain appliques on a five-dial instrument panel and glovebox door, deluxe simulated walnut-grain steering wheel, walnut-look, pistol grip door handles, brightly trimmed foot pedals, partial carpeted kick panels, with a bright center-strip molding, and red and white courtesy lights in the doors.
For visibility, the new five-dial instrument cluster of 1965½ and 1966 required a new low-profile Rally-Pac, as seen here. This 1966 GT has both the Interior Decor Group and the GT Equipment Group.
The standard Mustang interior for 1965 features bucket seats and a sweep-style instrument cluster. Bench-style seats were optional in the coupe and convertible.
Every 1966 Mustang has the five-dial instrument cluster. The plastic steering wheel and horn ring carried over from 1965.
Pony seats are the deluxe seats that are part of the Interior Decor Group, optional from the middle of the 1965 model year through 1966.
As visible here, rocker panel moldings were standard on the 1965 and 1966 fastback, but deleted with the GT package.
The factory deleted the standard rocker panels on this 1966 fastback because it is a GT. The rear valance is a GT featuring trumpet exhausts.
Ford redesigned the Rally-Pac for visibility with the new five-dial instrument cluster that came along midway through 1965 and was continued through 1966.