Axle won't go in far enough

I'm guessing on the SG, is it the clutch type? How did you install the thrust buttons? They are really pretty straightforward as far as installing them.

You should have minimal end play on the axle. Remember the thrust button is sandwiched between the two axles, essentially making it a "solid" shaft all the way through, if that makes sense. As far as hard to turn, it will be even with a tire on there, it should be resistant.

One thing, did you pack the bearings before you installed the axles?? Very important, they get no lubrication from the diff oil!!!

Once you get your axles in on the right side where the adjuster is take out the little retaining clip and tighten the the adjuster until you can feel no end play in the axle. Rap on end with a large hammer and turn axle a couple of times, go to left side and make sure that there is no end play there either. Now go back and back off the adjuster till you can just barely feel any movement turn axle a couple of times more to seat the bearings and recheck the movement. You should be able to feel a slight movement when you grab the axle flange and push in and out. Now replace the locking clip and put the drums back on.

Ideally you would want a dial indicator and set end play between .008 and .018, those are factory settings, I usually go for .010.

Hope this helps a little.