If it was a factory Pony/deluxe interior car, there will be several giveaways for '65. All deluxe interior Mustangs and factory GTs in 1965 received the '66-style instrument cluster with 5 gauges instead of the standard Falcon-style speedometer. On a standard interior car that's been converted to deluxe interior later in life, the instrument cluster swap is usually the hardest part since it involves cutting the dash and using a different underdash wiring harness. If you're wondering if the car originally came with the upgraded interior, pull the instrument cluster and take a look behind the dash. There should be a notch in the metal dash to clear the '66-style speedometer. If that notch is missing or looks like it was cut by hand, then the car started life as a standard interior car.
To answer the original question: if the car was a factory deluxe interior car, it came with the woodgrain steering wheel.
Also, welcome to the site!