rear end issues, tire rubbing on drivers side

Now the rear end shop I took my car to said that it needs a new axle? I guess you can slide the bearing on by hand?

Should I waist my time with the 7 1/4 or install the 8 1/4 I have at my house?
The guy I bought it from said it was fine and didn't have any problems. He switched to a 8 3/4.