1) GM for parts if they are still available.
2) Take it to a hose shop and have a new hose section fitted. Same cost as above likely.
3) Redneck it with some heater hose and clamps to replace just the hose sections. <-- This repair is known to leak now and then.
4) Junkyard...
This is a replace all the heater hoses and radiator hoses time if they are all the same age.