Dirtfarmer: I do not know the exact answer to your question "how rare are the 2" Model 34's".
But I do know they bring a 10% to 20% premium over comparable condition 4" Model 34's.
This is my observation from chasing them for the last several decades.
I have 3 (three) Model 34's with 2" barrels and have owned a couple more that were not up to my collector quality standards and they got resold.
Two of my Model 34's with 2" barrels are blued Model 34-1's and my third is a Model 34 of later vintage and is factory nickel finished in the original factory "nickel" (grayish) box.
I would guesstimate that 1 (one) out of 10 (ten) Model 34's are 2" barrel models.
I would love to hear others "estimates" on the rarity of the 2" Model 34's.
Hold into the wind
VarmintGuy