Steering Coupler I.D.

How many different steering couplers are there? I'm looking at 2 that are different lengths. One is out of my '74 Dart that has power steering. It measures 3 5/8" long. The other is one that I got with some other parts. It measures 3 1/32" long. Is the shorter one for manual steering? Is there more then 2 different ones?

Thanks in advance..................Ted