As I discuss in this answer, the Adi Parva of the Mahabharata describes exactly who incarnated as each of the major characters in the Mahabharata. Concerning Kripacharya, guru of the Pandavas and Kauravas, it says this:
And, O king, that Brahman sage who, on earth, was known by the name of Kripa and was the embodiment of all manliness was born of the tribe of the Rudras.
For those who don't know, the Rudras are a group of 11 Vedic gods associated with Shiva, as I discuss here and here. In several scriptures including this chapter of the Srimad Bhagavatam, their names are given as Manyu, Manu, Mahinasa, Mahān, Śiva, Ṛtadhvaja, Ugraretā, Bhava, Kāla, Vāmadeva and Dhṛtavrata.
So my question is, which of the Rudras was Kripacharya an incarnation of? Was he an incarnation of Shiva, or one of the other Rudras? Are there any scriptures that discuss this?