Driveline Options for the 1966 GTO

The following list contains the standard and optional driveline options for the 1966 GTO. The bold text for each option is used in the Top Speed Calculator. If your car is modified, use the closest match. You'll have a chance to make changes in the Top Speed Calculator page.

Select Engine for the Max RPM:

Standard 335hp (389cu in, V8, 1-4bbl, 335Hp, 5000RPM at Max Hp)
Optional Tri-Power (389cu in, V8, 1-4bbl, 360Hp, 5200RPM at Max Hp)

Select Transmission for the Gear Ratios:

Standard 3-Spd Man Column Shift, Saginaw M11 (1st 2.54:1, 2nd 1.50:1, 3rd 1.00:1, rev 2.63:1)
Optional 3-Spd Man Floor Shift, Dearborn M13 (1st 2.42:1, 2nd 1.61:1, 3rd 1.00:1, rev 2.33:1)
Optional 4-Spd Man Floor Shift, Muncie M20 (1st 2.52:1, 2nd 1.88:1, 3rd 1.46:1, 4th 1.00:1, rev 2.59:1)
Optional 4-Spd Man Close-Ratio Floor Shift, Muncie M21 (1st 2.20:1, 2nd 1.64:1, 3rd 1.28:1, 4th 1.00:1, rev 2.27:1)
Optional 2-Spd Auto Column/Floor Shift, Super Turbine 300 M31 (1st 1.76:1, 2nd 1.00:1, rev 1.76:1)

Select Rear Axle Ratio:

  Engine   Trans  
3.08		  
3.23		  
3.36		  
3.55		  
3.90		  
4.11*		  
4.33
  Std 335hp   3-Man   Opt   Opt   Opt   Std   Opt   Dlr   Opt
      3-Man w air   Opt   Std   .   .   .   .   .
      4-Man   Opt   Opt   Opt   Std   Opt   .   .
      4-Man w air   Opt   Std   .   .   .   .   .
      4-Man Close   .   .   .   .   Std   Dlr   .
      2-Auto   .   Std   Opt   Opt   Opt   .   Opt
      2-Auto w air   Std   Opt   .   .   .   .   .
  Tri-Power   3-Man   Opt   Opt   Opt   Std   Opt   Dlr   Opt
      3-Man w air   Opt   Std   .   .   .   .   .
      4-Man   Opt   Opt   Opt   Std   Opt   .   .
      4-Man w air   Opt   Std   .   .   .   .   .
      4-Man Close   .   .   .   .   Std   Dlr   .
      2-Auto   .   Opt   Opt   Std   Opt   .   Opt
      2-Auto w air   .   Std   .   .   .   .   .
 
* Dealer installed only after ordering 3.90 with 3-speed manual or 4-speed close ratio manual.

Select Tire Size:

Standard nylon cord red-line US Royal Tire Paw 7.75x14 (P197 / 90R14)*
Optional rayon cord whitewall 7.75x14 (P197 / 90R14)*
(* tire sizes are based on direct conversion for calculation purposes, they are not standard codes)