Looking for a few of the covers shown here. They're for Jamma and similar 56-pin ( 2 x 28 ) edge card connectors.
Eddie, perhaps you have some in that stash of yours? Unfortunately, Jamma's online store is closed at the moment and the Sept 17 Google cache of it was showing them as out of stock.
Protective_Connector_Shell_for_JAMMA_Harness_Angle_View_1024x761_1.jpg