Rear axle/brake Q's?

I might be wrong, But...I have bought all the new parts to swap my 8 3/4 to BBP. If he purchased aftermarket axles, they are same lenght, not offset. I believe what might have happened is he puchased Timken bearings with them, OEM, and not the green bearings which is non adjustable. They were probably not adjusted right from the beginning and wore them out prematurly.