OK, just compared part numbers and this is what I've learned.
The 1M has the same clutch disk as the 135i.
The pressure plate is, presumably, nearly identical to both the 135i and the 335is as only the last two numbers are different. The last three part numbers are: 250 (1M), 249 (135i) and 248 (335is).
The 1M flywheel is not shared by any other models. It's weight is listed as 25.13 lbs. Two different flywheels are listed for the 135i -- one 27.87 lbs and the other 29.51 lbs. Two different flywheels are also listed for the 335is -- one 28.37 lbs. and the other 30.18 lbs.
All for now.