Cheyenne tail turret on a B-17G

[seesul]

Hello to all. I have 2 questions related to the Cheyenne tail turret on G versions:

1. Is there any evidence since which S/N the B-17Gs were equipped by the Cheyenne tail turret in the Boeing, Douglas and Vega factories?
2. Is there any evidence which S/Ns (or at least production blocks) got this modification in the Cheyenne modification center (out of factories)?

Thank you

 

[CATCH 22]

Is there any evidence since which S/N the B-17Gs were equipped by the Cheyenne tail turret in the Boeing, Douglas and Vega factories?

I wouldn't call it evidence, it's more the information one can find here or there (books, internet). Here is a quote from Joe Baugher's site e.g. :
The so-called "Cheyenne" tail gun mounting modifications were incorporated in the B-17G-80-BO, -45-DL, -55-VE and subsequent batches. These tail gun mountings also had a reflector gunsight instead of the previous ring and bead. With this installation, these B-17Gs were five inches shorter than the earlier versions.
And the same from the Crowood book with the serials:

 

[macharvard]

I wouldn't call it evidence, it's more the information one can find here or there (books, internet). Here is a quote from Joe Baugher's site e.g. :
The so-called "Cheyenne" tail gun mounting modifications were incorporated in the B-17G-80-BO, -45-DL, -55-VE and subsequent batches. These tail gun mountings also had a reflector gunsight instead of the previous ring and bead. With this installation, these B-17Gs were five inches shorter than the earlier versions.
And the same from the Crowood book with the serials:
View attachment 583208

For those who may not be 'metricized', there is an error in the scan above, whch states that the B-17's length was shortened by 5" or 2.5 cm. That should be 12.5 cm.