For those of you who use Fr. Weber's wonderful "The Proper of Mass," but are OCD enough to be irritated by the occasional deviation from the Graduale Romanum tone like me, here is the Introit for the 18th Sunday in Ordinary Time (Years B & C) based on the tune. I used the GR text (Solesmes translation) which is slightly different than the Roman Missal:

GR - Psalm 69: 2, 3, 4
RM - Psalm 69: 2, 6

Additionally, I set the GR introit for the 18th Sunday, Year A in English based on the GR tone. They are both available in the PDF below.