Dynatrac has two versions, both knurled and smooth body? I wonder if the two have the same diameter?
You will have to call DynaTrac and get the info on the differences. McQuay Norris has the same type of BJ's but their's are intended for installation ease not a problem solver like some. They are grooved not splined and should be about the same size as the smooth ones. The grooves are to add instalation straight into the bores becasue the way they sit in the axle C's it is easy to get them out aligment on install.