The last time I looked into New Jersey marriage indices I was told by a volunteer at the LDS Family History Center that there is an index but that you must go to Trenton to look at it. The State of New Jersey had refused to allow the Mormons to film it. However, I was also told that the state was reconsidering its position since making the indices available through LDS Family History Centers would reduce the amount of time state workers spend on genealogy related requests. Check with your local Family History Center.