70 above 73 and up below. You can see how beefier the axles are. They were a little longer than than the old ones too. Is your 71 a disc brake axle? If it is the newer shafts will go right in. Mine was drum brakes. I had to swap the knuckles to get them to fit. I know your question was about u-joints but wanted to show this too. Its a good upgrade.
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