BMW dealers sell VEM-V20991274.
The thermostat housing has an integrated sensor. It's easy to replace. I didn't find an aluminum housing when searching for an M54. I copied and pasted from an excel spreadsheet. I'll correct the oil thermostat number.

For O-rings, I bought a kit off eBay. I carry O-rings in a bag. Most O-rings can be replaced in a parking lot if needed. Most hoses fail because the metal hose ring fails to seal over time.

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'06 X5 3.0i - bought @143,123 miles (12/26/20)