If I remember correctly...
Well, when you first cut the shaft, how did you figure/estimate what length you be able to use?
I installed the shaft coupler on the spline and I put the new agitator in the tub and let it rest on the tub bottom. Next I took a rigid metal tape measure and fed the tape down the center of the agitator until the tape reached the top of the Maytag transmission splines. I measured from the top of the agitator to the top of the splines.