You hear a lot about Subarus being picky about axles, about “New, made in China” replacement axles not being great, and that Subaru axles are the only ones to use on your Subie. Now, I add my voice to these anecdotes.
The top axle in the picture is a Cardone Select 66-7055, “new, made in China,” and ostensibly the correct axle for my ‘98 Subaru Legacy Outback. I installed it about 2 years ago and I have regretted it ever since. Odd vibrations and noises started about the same time I installed this axle.
The bottom axle in the picture is a genuine Subaru remanufactured axle, part no SOA966H900R1. I installed this today, and my car now runs smooth and quiet. Or, at least as quiet as can be expected of a 18 year old station wagon.
Notice how they aren’t the same length? The Subaru axle is slightly, but measurably shorter than the aftermarket. The splined portion on the hub end seems just a hair shorter as well, although I didn’t measure it.
The boots on the Subaru axle are made of a heavy rubbery material, while the aftermarket boots feel thin and plasticy (and what’s with the weird shape of the inner boot?).
The Subaru axle is much more expensive (about 3x the price of the Cardone), but I feel strongly that it’ll last at least as long as the rest of the car does.