The importance of measuring bell housing runout.

Remember that while you are working on aligning the center-line of the crankshaft to the centerline of the transmission by using dowels, you must also insure the bell-housing sits squarely on the back of the block.

This is to verify the transmission centerline sits both square and plumb in relation to the crank centerline.

I've had to use shims between the block and bellhousing face to get the transmission to sit square and plump to the crank centerline. This is in addition to centering transmission input to the mounting hole.