I have a 56 235 inline 6 cylinder with a 4 spd tranny. I just went through this myself. If it is like mine in order to get the clutch housing as the manaul calls it (bellhousing for automatics) you will have to remove the clutch and pressure plate, then remove the flywheel. On mine there was 2 bolts coming from the motor into the clutch housing which were easy to get to and 4 bolts behind the fly wheel going into the motor which were not so easy to get to. Mine there was no way to remove the clutch housing without removing the flywheel. Automatics I am not sure however I assume they mount the same or similiar. My motor was frozen so I had to do a heck of a lot of work more but I got errrr done.
"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my sweet ride." -Amen
56 Chevy 3100 
