I love RBN but this is one department (other being jazz) where we are seriously lacking. All death metal in RBN is either deathcore or modern technical/melodic death metal. The only song I'd classify old school death metal is Impaled's The Last Gasp, which I love.
It could be anything, whether it was Autopsy, Death, Dismember, Interment, Cannabis Corpse, Coffins, Morbus Chron, Hooded Menace, I don't really care as it all rocks and would be very fun to play as the songs usually have more variation than just constant blasting.
And no, new Morbid Angel is not very old school.