Part number 99610614756Source-mentioned candidate. Verify fitment and availability independently.
Cited source accounts
uh ohhh...coolant expansion tank should be OE Porsche only, unless you want to do it again real soon. Sadly Coolant Reservoir For 996 - New/Replacement S99610614756 Coolant Reservoir For 996 for Porsche 911 $1,126.84 That's AutoAtlanta price. I don't know about Sunset Porsche or Suncoast parts prices.
Replace the coolant expansion tank
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