This excellent set of reproduction replaces the no longer available factory parts and is the plastic cap that fits at the rear top of the door and finishes off the squeegee. each easily installs with two screws, one of which holds the rear window guide channel. Set of left and right caps.
Kit consists of:

1 - b91454217310 - left side window rear cap 1973-76 914 - normally $16.38

1 - b91454217410 - right side window rear cap, 1973-76 914 - normally $16.38