Think they're probably talking about the axle housing ends on the 9" Fords, there are big and small ends. The bigger the bearing, the more load (abuse) it will take. I'd suggest a 9" Ford with a full spool and aftermarket axles, Currie, Moser, Strange, etc.... A 35 spline axle should do it, to be sure and to have in the future should you add some horsepower might want to spend the big bucks and get the 40 spline axles now.