To find out what GM cars use the AC bracket part number 10055800, I recommend you:
1. Check a reputable online parts catalog: Websites like RockAuto, AutoZone, Advance Auto Parts, and others usually have searchable databases that can identify vehicles using a specific part number.
2. Contact a GM dealership: Your local GM dealership should have access to the most up-to-date information on part compatibility.
3. Use a parts search engine: Specialized search engines like Car-Part.com or PartSouq.com can often help you find the compatible vehicles for a specific part.
Remember that even if two vehicles share the same part number, there might be minor variations or revisions to the part over time. It's always best to confirm compatibility with the specific year, make, and model of your vehicle.