The other day I posted a Harpy illustration from the 1977 DnD Monster and Treasure Assortment accessory. Chevski and Spielmeister noted that it appeared to be a David A. Trampier piece. Well, here's further evidence supporting that. The Harpy from the AD&D Monster Manual. It has the same feathered body, hair and shaded wings as the illustration from the M&TA, and is signed with "DAT".
I was visiting The Sentry Box several days ago, and happened upon an old Goodman Games "Dungeon Classics" module, that features Harpies. I will have to pick that up, to see if it is any good.