Hey, welcome to the site. I'm Michael too. 1964.5 and 1965 had a horizontal bar speedometer with 2 gauges at the ends, fuel on the left, and temp on the right,3 red warning lights,1 for the hi beams, 1 for the oil pressure, and in 64.5 the other light was a warning light for the generator, in 65 it was a warning light for the alternator, and there was only one green light for the indicators.
In 1965 the GT or pony interior got a 5 gauge instrument cluster with a speedometer in the center, then going from the center to the outside of the cluster, to the left there is the oil pressure and the fuel gauge on the end, and on the right there is the electricity gauge (amp meter), then on the right outside is the temperature gauge.
Also, in 1964.5 and 1965 the glove box door was curved to match the dash, where as 1966 they made the front of the door flat.
In 1965 and 1966, there was also an accessory called the "Rally-Pac" In 1965 and 1966 the Mustangs didn't come with a tach or a clock. The rally-pac was attached to the steering column and it had a tach on the left and a clock on the right.
In 1966, my car's year, they made the 5 gauge instrument panel standard. Then it would be either be the standard black camera case finish, or it would be the woodgrain, like I upgraded my car to.
In 1967 they kept the 5 gauges, but they arranged it with 3 small gauges evenly spaced across the top, and between them on the bottom were 2 large gauges. Starting at the top left working our way across the top, then going down to the bottom right is this. The top left gauge is the gas gauge, the center gauge appears to be a clock or just a blank gauge face, then the top gauge on the right is the Temperature. The large gauge on the bottom left is the Speedometer, and the the large gauge on the right on standard cars is actually 2 gauges. The top is the Oil Pressure, and the bottom is the Alternator gauge. On GT cars, the large gauge on the bottom right is a tachometer instead. They also have a red idiot light as a brake warning light.
Hope this helps you. I am including pictures of the 64.5/65, 66, and 67 instrument panels, and a picture of a 1966 rally-pac installed on a 64.5 or 65 instrument panel. The 65 rally-pac is supposed to be hooded and have a filler panel between the gauges.
I hope this helps you. | 
dne' here!
