Here's the Info on the Transmissions that will be offered in the G8.

The base G8 model receives a 3.6L DOHC V-6 with variable valve timing, rated at 261 horsepower (194 kW). It is paired with a five-speed automatic transmission with manual shift mode.

The G8 GT is powered by a uniquely configured 6.0L small-block V-8, rated at 362 horsepower (270 kW) and 391 lb.-ft. of torque (530 Nm). A six-speed automatic transmission with manual shift mode is standard and features the fuel-saving Active Fuel Management system, which enhances fuel economy by alternating between eight- and four-cylinder power. An optional six-speed manual transmission will be available soon after launch.

A limited-slip rear differential is standard with GT models.

• Transmission
  • Hydra-Matic 5L40 5-spd automatic
    • Gear Ratios
      • 1st: 3.42
      • 2nd: 2.21
      • 3rd: 1.60
      • 4th: 1.00
      • 5th: 0.75
      • Reverse: 3.02
    • Final Drive Ratio
      • 2.92
  • Hydra-Matic 6L80 6-speed automatic
    • Gear Ratios
      • 1st: 4.03
      • 2nd: 2.36
      • 3rd: 1.53
      • 4th: 1.15
      • 5th: 0.85
      • 6th: 0.67
      • Reverse: TBD
    • Final Drive Ratio
      • 2.92
  • TR6060- six-speed manual
    • Gear Ratios
      • 1st: 3.01
      • 2nd: 2.07
      • 3rd: 1.43
      • 4th: 1.00
      • 5th: 0.84
      • 6th: 0.57
      • Reverse: TBD
    • Final Drive Ratio
      • 3.27