Anybody who has dialed in a bellhousing knows it is a real pain. I am putting a new motor in the car this winter and a friend of mine tells me to borrow his Browell bellhousing alignment tool to get the bellhousing indexed properly. Holy crap in 15 minutes I had the bellhousing all indexed. This tool hits it out of the park in my opinion.
You bolt the locating fixture on the crank, bolt up the bellhousing, then slide the black collar to try to slide it into the bellhousing center hole. If it slides in then you are good, if not use some offset dowels to be able to slide the collar in the center hole.
