I dial flywheel housings in. Your transmission input shaft depends on this for alignment. If there is misalignment, it will cause wear on the input bearing and improper mesh of gears. I have seen people who mounted flywheel housings that were warped in a fire and the transmission would jump out of high gear when he they let off the gas. I think this is probably one of the most ignored check to spec things there is in light vehicles. However, with the over the road trucks I have operated for over 45 years, dialing in the bell housing is just a way of life.