for our customers we have two alternatives in stock vs part 603-1408-ND (EFB1524SHG from Delta Electronics as FAN AXIAL 172X50.8MM 24VDC WIRE):
6424R-343 from ebm-papst Inc.. as FAN AXL 171.5X50.8MM 24VDC TERM with 497 pcs Immediately available
or
OD172SAP-24HBXC from Orion Fans as FAN AXIAL 172X50.8MM 24VDC WIRE with 63 pcs Immediately available and additional 650 pcs in their Factory
Easily compare all part similarities and differences here: https://www.digikey.de/en/cross-reference?search=EFB1524SHG