I had to move about 20 axles from my bone pile to get to my single wide tread FC 150 axle this afternoon. My FSM, 1960 edition, clearly shows a width of 57" for these. My axle is from a 63 I think (data is stamped on tube but haven't yet looked it up) and the WMS/WMS is very close to 59". So did Kaiser extend the width another 2" on these between 1960 and 1963????