This is the ESL10520 water pump, and it's built to fit Farmtrac tractors – specifically the 545, 555, and 665 models.
It's a brand new, aftermarket part from Reliable Aftermarket Parts (they're pretty straightforward with the name, right?
).
It's still in its original packaging, so no worries about damage or wear.

The part numbers include ESL10520, 2706-6001, and ESL10520-A – so if any of those match your old pump, you're golden.

This pump replaces the factory unit and keeps your tractor's engine cool even during heavy field work.