A833OD with worn output spline

I'm beginning to think the slip yoke splines on the cast iron OD units are a little different than everything else. I bought a new yoke from Brewer's and it fits my '68 A-body unit perfectly, but on my cast iron OD shaft the new yoke will go on about two inches VERY TIGHT and then stops, and I have to use a rubber mallet to get it back off. Both are 30 spline. And you say you have a new yoke that fits your OD shaft too loose? I am very confused.