67 non-disc master cylinder bail change date?

[jeffschevelle]

Has anyone ever determined when the bail on a 1967 non-disc master cylinder changed from the one that is straight on the front and rear (the vertical parts) to the one that has a dog-leg on each end?  I know why it probably was changed (the bend allows the bail to "flex" more and makes it easier to get on and off the lid), but I don't know exactly when it changed.  I know my 12A 67 Chevelle had the straight bail, and my 05C 67 Chevelle has the dog-legged bail, but don't know where in between it changed.

Thanks!  Jeff

[jeffschevelle]

A friend just told me that his survivor 03D 67 Chevelle has the dog-legged bail, which narrows it down to somewhere between 12A and 03D. 

[1967butternut]

My 02B 67 with manual drum brakes has the bent bale.

I believe it's original to the car but couldn't swear to it since I've only had the car since 1975.