71 Dodge Dart Swinger in England

Got the transmission out and old flex plate off and swapped out for a B&M balanced flex plate.With the transmission on the floor I was able to get the stuck yoke removed. It would not slide on and out and needed quite a bit of force to remove. Looking at the splines on the yoke they seem quite square edged compared to the splines on the transmission (see photos below). Also the yoke has had some machining at the end to remove about 1 1/2" of the splines so its been modified to fit. Hence I'm thinking either the machining has left a burr on the end of the splines causing it to be tight, or its the wrong spline/yoke, as it is a ford 9" diff, maybe the PO used a full ford propshaft? the markings on the yoke say 'W4' and '434' does this identify the yoke as either mopar or ford?
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