While you can switch out the center chunks, I believe you will find the axel housings do not share the same control arm mounting points. Perhaps someone else can confirm. Want to say only 67 and 68 are direct housing swaps.
I installed a 3:42 posi in my 68 Bonneville, and truthfully, I wish I had left the open 2:73. The off the line performance change was not that great with the low-po low compression 400, and I lost some of the easy highway cruising ability.
Are you building something with enough grunt and planning to use it in a fashion that really needs the posi?
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