Steering coupler and master spline questions

Hey guys,

I have a 1973 duster im putting back together, I'm trying to put back in the steering column at the moment and I ran into a problem.

I lined up the notch on the coupler with the master spline on the power steering gear and attempted to put it on, it gets to where the groove for the pin goes and won't budge any more.

I took it off made sure it was clean and I had it lined up then I noticed there were 2 master splines one was divot and the other was a wide spline 180° from each other.

which spline do I line the notch on the coupler up to or did I buy the wrong power steering gear.

Thanks,
Damien

P.S. pictures can be provided if y'all need them I'm just at school so I can't take any at the moment.
You might look deep into the coupling and see if the splines are uniform all the way to the end. Could be a bad area that needs cleaned up. A triangle file works wonders sometimes.