hijump -
If your questions regarding Grade V mobilization are directed at a patient with neck pain, you may want to consider these references, all of which document the benefit of thoracic spine manipulation for the treatments of patients with neck pain. It is a very safe region of the spine to perform a thrust technique on, and anecdotaly I've found it an "easier" technique to perform.

LinksFernández-de-las-Peñas C, Palomeque-del-Cerro L, Rodríguez-Blanco C, Gómez-Conesa A, Miangolarra-Page JC.

Changes in neck pain and active range of motion after a single thoracic spine manipulation in subjects presenting with mechanical neck pain: a case series.
J Manipulative Physiol Ther. 2007 May;30(4):312-20.
PMID: 17509440 [PubMed - indexed for MEDLINE]

Cleland JA, Glynn P, Whitman JM, Eberhart SL, MacDonald C, Childs JD.

Short-term effects of thrust versus nonthrust mobilization/manipulation directed at the thoracic spine in patients with neck pain: a randomized clinical trial.
Phys Ther. 2007 Apr;87(4):431-40. Epub 2007 Mar 6.
PMID: 17341509 [PubMed - indexed for MEDLINE]

Cleland JA, Childs JD, Fritz JM, Whitman JM, Eberhart SL.

Development of a clinical prediction rule for guiding treatment of a subgroup of patients with neck pain: use of thoracic spine manipulation, exercise, and patient education.
Phys Ther. 2007 Jan;87(1):9-23. Epub 2006 Dec 1.
PMID: 17142640 [PubMed - indexed for MEDLINE]