This is the 4th Generation F body radiator overflow and battery support also.

GM part.. exactly as shown.

(Note.. these bottles are a PITA as they tend to leak between the battery tray platform and the resevior bottle under it.. no known fix and 80% of the ones coming out of GM are all the same... we CAN NOT guarentee the life these.. it may need additional sealing fitting into the gap.... this is a ongoing problem and we are looking for a solution but it seems the Canadian manufacturer for this part is primarily responsible.  IE  again.. we can supply you one if needed but be aware that we will not guarentee on GM USA's behalf the life of these for one day due to the impractical way it has been made with a heavy battery sitting on top of a delicate sealed canister... just bloody stupid....!)