Putting my B2620 back together and the mid front axel drive U joint line would not go onto its drive shaft. A closer look reveled this! Cost of a new U Joint $130 cost of further damage .
I am not sure how you can tell.I blew up the photo and its a broken spline.
Nothing I ever broached /keyed looked like thatI am not sure how you can tell.
Think about the machining process to make this component. It may be easier to make ALL the splines then machine one off later when the phasing is known. This could leave behind something which APPEARS to be the remnants of a spline.