New Buna-N Nitrile Square O-Ring to fit Ford 5.8 engines with Modine "sandwich" oil coolers. This seal fits between the oil cooler and the engine block.

If your oil cooler looks like mine in the second picture, this will fit your truck.

Fits F-150, F-250, F-350, Bronco, Econoline Van with the 5.8/351W engine.

This seal is not available separately from Ford.

I have sold hundreds of these since 2016 and installed them myself and never had any complaints.