Where can buy this parts？
Try ebay or your local salvage yard..
That is a water pump hose, the other end should connect to the radiator, you should be able to get that from your locale parts store.
Yea, just a coolant hose, here is a sight that has the hoses, just see which one it is, I think it is this first one... https://www.carid.com/acdelco/professional-hvac-heater-hose-mpn-14155s.html?singleid=73494669&url=1204287
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