Rear axels

Hi all,
As you know my G22 has the 7 1/4" rear axel. I have been told that the 8 1/4" is better and stronger. I do not know why my G22 had the smaller one as the engine is a 3.18.
Anyway, I may have come across a 8 1/4" locally from a Dodge Dart.
Will that one be all right "Straight put on" or must it be modified? I believe the photo is from that axel the seller has
Any help most appreciated, hint and tips.
Regards
Gunnar

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