Question about rarity and survivability of m1 carbines

I have two questions, that I am aware cannot be answered definitively, but would like to hear your educated opinions of:

• Which M1 carbine do you think is the rarest?
  
• What do you think is the survival rate for the rest of the carbine manufactures? For example, knowing that so many Rockola's were made, how many do you think still exist around the world?

Does the carbine club's past newsletters have information about these questions?

Tool Room models and EXP models. Some are one and two of a kind.
Forty to fifty percent. about 2.5 million.
Yes, some of it.

Maybe not a one of a kind.

Winchester had a 10 unit block 4,075,000 to 4,075,009

I don't know if those serial numbers were even used. I have never seen anything on them reported. But I think one from that group would be a nice find.