Question about spline count

[Matt68]

1973 Plymouth Barracuda. Originally a 318 car. My question is, should I have a 24 or 19 spline 727? Is there one count that is typically in a '73 Barracuda? Trying to buy a new Converter and need to know the spline count hopefully without having to drop the trans.

 

[marksmopars]

23 spline was small block application, 19 spline was big block as it was perceived to be a stronger design for th e larger amount of torque produced. Hope that helps

 

[Matt68]

@marksmopars you do mean 24 spline, not 23, correct? What's the difference in 23 vs 24 spline applications? How can I know which one I need with dropping the trans?

 

[Vaanth]

NOTE: Assuming no changes to original input shafts in the transmission in the following listing.



The 1962-1966 A727 Torqueflite input shaft has 19 splines.

The 1967- 1977 A727 Torqueflite and 1978-1991 A727 Torqueflite with non-lockup converter input shaft has 24 splines.

The 1978-1990 A727 Torqueflite with lockup converter input shaft has 23 splines plus a smooth machined area without splines at the nose of the shaft.

The A518 Torqueflite with overdrive, that replaced the A727, input shaft also has 23 splines.



The 1960-1967 A904 Torqueflite input shaft has 18 splines.

The 1968-1977 A904 Torqueflite input shaft has 27 splines.

The 1978~2002 A904, including A998 and A999, Torqueflite with lockup converter input shaft has 26 splines plus a smooth machined area without splines at the nose of the shaft.

The A500 Torqueflite with overdrive, that replaced the A904, input shaft also has 26 splines.

 

[marksmopars]

@marksmopars you do mean 24 spline, not 23, correct? What's the difference in 23 vs 24 spline applications? How can I know which one I need with dropping the trans?

View attachment 136622

I think Vaanth put it as clear as possible, it appears he has more information on this than I do so I bow to his expertise and offer my thanks to him for the information.

 

[Matt68]

@Vaanth last question; does converter diameter matter at all? I see 10", 11" 12"?

 

[Vaanth]

@Vaanth last question; does converter diameter matter at all? I see 10", 11" 12"?

In regard to the input spline size, the converter diameter does not matter.

 

[cudamark]

1973 Plymouth Barracuda. Originally a 318 car. My question is, should I have a 24 or 19 spline 727? Is there one count that is typically in a '73 Barracuda? Trying to buy a new Converter and need to know the spline count hopefully without having to drop the trans.

Get the numbers that are stamped on the pan rail to verify which transmission it is, and then order one for that model.