For all of you looking to retrofit, when there are separate "AUSTIN" parts in the catalog, I recommend NOT buying the "AUSTIN" parts for a Fremont-built Y, and similarly avoiding non-"AUSTIN" parts for an Austin-built Y. There is some reason why a different part number is used for Austin, could be some mounting / dimensional / attachment difference. Even worse would be if the parts bolted right up but didn't actually function correctly for the chassis, e.g. damper stroke differences resulting in reaching bump stops too soon or too late.
Personally I would also wait for someone with a brand new Y that has the new comfortable suspension, built in the same factory as your (so same chassis), to confirm exactly what suspension parts they have incl. revision letters.
Of course it's your time and money and hassle if you end up buying incompatible or otherwise incorrect parts, do what you're comfortable with! That is just how I would go about this if I had a Y and wanted to do this swap.
Lastly, when you have your original suspension off of the car, I would examine and measure carefully for any dimensional differences, just in case. Though if your new parts are simply a newer revision (letter) of the same numerical part number, then they SHOULD be completely compatible. (keyword: "should"
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Edit: It's very possible the "AUSTIN" parts are fully compatible with existing Fremont Model Y. I haven't seen anything in this thread yet to attest to that however. Someone needs to be the guinea pig and try it, and report back with all the details including testing full suspension articulation and bump stop engagement. If you're comfortable being that guinea pig and potentially being stuck with parts you bought but can't use, go for it! Just be aware of the risk.