Confused on which axle I need; 1977 magnesium 915

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So in my last thread, I realized my axle decided to leave my car on the highway, which was super not cool of it.

Today marks the 1 year aniv of my car breaking down, so I really want to fix it ASAP so I can get it back out this season.

I am really confused as to which axle I need for my car. Some of the parts I ordered for my transmission didn't fit, because 1977 is some weird ass year where there were parts changed during the run of cars.

So my 915 has a mag case. I just measured the flanges on the transmission, and they are 100mm, not 108mm.

So.... what part number do I need here?

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Is it this? 923 332 033 02

The parts catalog only ads to the confusion:

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I did just find this... which i think verifies the part number I listed above is correct? If someone could verify it'd be awesome not to buy the wrong part lol

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Here's what I had in my bone-stock '77:

P/N: 923-332-033-02-M60