If you have a Hulme Case Feeder and both machines are drilled and taped for mounting the case feeder, there is no reason you can't switch it between the machines. The M3 top plate (also the M2) top plate is for both 45 ACP and 38 Special. You just have to remove the top plate and rotate the top plate 180 degrees to change calibers.
On some Star reloaders, the tool head comes down a little lower than on others and the top plate can interfere with the travel of the tool head. This is not specific to Progressives or Universals, it's just how some machines were assembled. In a situation where this occurs, the top of the top plate that extends under the tool head must be milled a little bit to eliminate the interference.
Bruce Williams
Star Machine Works