Which rearend housing for an earlier 1966 car?

[cboss70]

Do all 66 Shelby's have the 9" with the rear bump out or did some of the early non-carry over cars have the round back? I have a friend with a car with a December build date (maybe around car 300+- cant recall) and I assume it's one with the bump out (not round back housing) but figured you never know since his car also originally had overrides.  Was there a transition date for the two housing styles? 

[GT350Lad]

As far as I know only carryovers had the 65 style. If your vin has 6R09K it's a humped housing.

[cboss70]

Thanks, If the 5/6 VIN is the deciding factor I'll just tell him to take a look and use that as a guide.  Thanks for your help.

[98SVT - was 06GT]

Was there a specific date change? The Mustang K collectors may have an actual production date for when changes occured.

https://hipo-mustang.com/

[J_Speegle]

Was there a specific date change? .............The Mustang K collectors may have an actual production date for when changes occured.

At least at San Jose likely not it appears. More likely a range when it too place would be the closest we could/can determine. Two problems - #1 we don't know specifically when each car was built (as Mustangs) and #2 when the change over took place they likely used up what was in the supply pipeline and in the small inventory at the car and at Sterling that supplied them and they likely were not concerned about which got used in any particular order since the change did not affect any of the other parts on the car unlike other running changes that took place (example change over from generator to alternator where there were a bunch of related parts that needed to be changed all at the same time.