I was looking up rear axles and noticed that the part numbers had changed in 2015. Does anyone know why. I'm currently working on a binding problem back there and trying to figure out what I have to work with.

make sure you check the mounts that hold the rear end in mine loosened up and caused a binding problem and just about ripped the front mount outa the frame

That's how it all started. Busted mount bolt, then it all worked loose. Went to swap out the shocks after i fixed it. Found out that the a arms won't swing down. The differential is mounted way too low and the axle bottoms in its socket. It does this a little with stock shocks but with longer ones, it's a lot more pressure on everything. I have to do something about it. Not sure if the EX has the same thing going on but the 53" sure does.

I know they do have one part number that is a longer axle.  The right rear axle in mine was too short and kept popping out of the differential.

Must have made them longer on the spline that goes into the diff. or moved the snap ring grove closer to the end. I will have more time to look at it the rest of the week. If I find a decent fix for this, I will let you guys know. I did notice the 500 and 800 diffs are mounted close to the middle of the arms like they should be. I hope they gave the designer and the guy who gave the OK to ship these the boot. I have worked in Mfg. most of my life and this didn't slip by them, someone knew about it.