You'll have to venture up to Pasadena and check-out my E3 Alpina. There is a metal bracket for each rear headreast that bolts to the trunk side of the rear bulkhead. This provides the ability to set the headreast at more than one height. The black plastic protective covers that cover the holes in the rear parcel shelf are to guide the headreast and also protect the rear parcel shelf material.
Gary Hesse
BTW, tomorrow, Saturday 8/23, from ~11 to 3, is open house at Ireland Engineering for the SoCal Vintage BMW Group and also Car Nite members. Come on up and then we'll go 10 minutes up to my place in Pasadena.