checking rear end housing straightness

I measured the height of the tube & on (on side of the pumpkin) 3 measurements along that length were equal but on the other side the measurement at the outer end (near the perch) was 1/8" off and I pullled both axles & one went back in easily but the other one needed some tapping. is it time to source another one? RR
Is the rear end in the car? Is the rear end locked? If you answer these two questions I can explain which method to use to check the rear end for straightness.