I don't know what it's like for Subaru, but when I had a mirror break I looked into getting just the glass from a dealer, but alas, had to buy the whole assembly instead. For the crackpot prices they wanted for it, I ended up going to a glass/mirror making mob in Wangara somewhere and they cut and glued a new piece of glass in for me at less than half the cost of a new assembly. Looks exactly the same as the mirror on the other side, so personally, would go down this path again if it happens.

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Air is for pussies.