I just received in the mail today, through the used book market, a packet of eight tapes with accompanying study guide, The Epistle to the Hebrew, by George MacRae. MacRae was most notably the Charles Chauncy Stillman Professor of Roman Catholic Studies at Harvard Divinity School from 1973 to 1985 before his untimely death. He was a notable NT scholar. I was not aware until recently that these tapes existed, but I did know that MacRae wrote a small commentary on Hebrews for the Collegeville Bible Commentary, as well as a couple of important articles:
MacRae, George W. "Heavenly Temple and Eschatology in the Letter to the Hebrews." Semeia 12 (1978): 179-99.
MacRae, George. "A Kingdom that Cannot Be Shaken: The Heavenly Jerusalem in the Letter to the Hebrews." Pages 27-40 in Spirituality and Ecumenism. Tantur/Jerusalem: Ecumenical Institute for Theological Research, 1980.