Looks like a reconditioned o-ring/gasket. The original with square edges, the new one is round but has stopped that pesky 5.0 leak that occurs at the top hose.
π Enhance Vehicle Performance with the Timken 510050 Wheel Bearing
9 Review
Enhanced Performance: Melling Hi Volume Oil Pump for 4.6 5.4 Modular Ford - 20% more volume than stock (Model M340HV)
8 Review
π Timken WB000020 Front Wheel Bearing: Optimal Performance for Your Vehicle's Front Wheel
8 Review
LED office lamp Baseus i-wok DGIWK-P01, 5 W, armature color: black
13 Review