Driveline Options for the 1968 GTO

The following list contains the standard and optional driveline options for the 1968 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 350hp (400cu in, V8, 1-4bbl, 350Hp, 5000RPM at Max Hp)
Optional HO (400cu in, V8, 1-4bbl, 360Hp, 5100RPM at Max Hp)
Optional Ram-Air I (400cu in, V8, 1-4bbl, 366Hp, 5400RPM at Max Hp)
Optional Ram-Air II (400cu in, V8, 1-4bbl, 366Hp, 5400RPM at Max Hp)
Optional Economy (400cu in, V8, 1-2bbl, 265Hp, 4600RPM at Max Hp)

Select Transmission for the Gear Ratios:

Standard 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 3-Spd Auto Column/Floor Shift, Turbo-Hydramatic M40 (1st 2.48:1, 2nd 1.48:1, 3rd 1.00:1, rev 2.08:1)

Select Rear Axle Ratio:

  Engine   Trans  
2.56		  
2.78		  
2.93		  
3.08		  
3.23		  
3.36		  
3.55		  
3.90		  
4.11*		  
4.33
  Ecomony   Auto   Opt   .   Std   .   Opt   .   .   .   .   .
      Auto w air   .   Std   .   .   Opt   .   .   .   .   .
  Std 350hp   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   .   .   .   .   .   .   .   Opt   Dlr   Opt
      3-Auto   .   .   .   .   Opt   Std   Opt   Opt   .   Opt
      3-Auto w air   .   .   Std   .   Opt   .   .   .   .   .
  HO   3-Man   .   .   .   Opt   Opt   Opt   Std   Opt   Dlr   Opt
      3-Man w air   .   .   .   Opt   Std   .   .   .   .   .
      4-Man   .   .   .   Opt   Opt   Opt   Std   .   .   .
      4-Man w air   .   .   .   Opt   Std   .   .   .   .   .
      4-Man Close   .   .   .   .   .   .   .   Opt   Dlr   Opt
      3-Auto   .   .   .   .   .   Opt   Std   Opt   .   Opt
      3-Auto w air   .   .   .   .   Std   .   .   .   .   .
  Ram-Air II   4-Man Close   .   .   .   .   .   .   .   .   .   Std
      3-Auto   .   .   .   .   .   .   .   .   .   Std
                                           
 
* Dealer installed only after ordering 3.90 with 3-speed manual or 4-speed close ratio manual.

Select Tire Size:

Standard Fastrak red-line G77x14 (P219 / 77R14)*
Optional Fastrak whitewall G77x14 (P219 / 77R14)*
Optional wide oval red-line F70x14 (P215 / 70R14)
Optional wide oval whitewall F70x14 (P215 / 70R14)
Optional radial 205Rx14 (P205 / 82R14)*
(* tire sizes are based on direct conversion for calculation purposes, they are not standard codes)