904 speedo gear. Long or short shaft?

[Phil21502]

Need a new speedo gear for my 74 dart sport with a 904. I see both a short shaft and a long shaft available. Which do I need?

 

[Locomotion]

Long. They started changing them a few years later.

Do you know what tooth count you need ?

[FOR SALE] - 727/904/833 speedometer gears & related parts.