That's a lot of questions.
The 3-speed shaft on the driver's side of the clutch housing is pressed in.
The geometry of the bottom of the truck clutch housing changed in 1954. The angles in the frame fross member changed.
The 216/235/261 flywheels can be mounted interchangeably. Use the clutch assembly that works on the flywheel you are using (including the throwout bearing). Use the starter that matches the year/teeth for the flywheel, 6v or 12v starter/flywheel combination.
Mechanical foot-operated starters were used up to 1959.
