Shift Coupler Spline Question

[gtc]

I bought a shift coupler a while back to rebush and swap out with the one in my car. I've noticed that the splines on the input side of the coupler in my '84 run lengthwise along the rod, while the splines on the spare coupler are turned 90 degrees - what I would call ribs instead of splines. (See crappy MS Paint illustrations)



Was this type of spline pattern used on certain year cars / transmissions?

Thanks,