If you cut it off and the reason it wouldn't go in was because the cone and side gear splines weren't lined up you'll wind up with a junk axle and a car that won't move! You need to get someone that knows 8 3/4's to see what you have going on!
Agreed. Cutting the axle may make it go in but if it doesn't engage into the inner spline the car won't move and you might destroy the sure grip unit to boot. I just read through the whole thread and it sure sounds like it's just a spline not aligned. Seen it happen several times. You just need to do what SG said earlier. Bolt the other axle in and put a tire on that side then put the side in that isn't going all the way and using a pry bar lodged in the wheel studs turn it while pushing in. It won't be easy but it'll go.