67 Spec Case Question

[gt350hr]

   67_1183,
        Thank you for the pictures , saves me from crawling under my '66. That shows the casting patterns were transferred to the special foundry for use and are identical. You have noted the difficulty ( because of no date association) on when the SPEC cases were cast. Now as for "how" you got one and Brett's car didn't , I offer this. Drum to drum assemblies were "built" in mass at the assembly plant ( obviously) in advance of the cars hitting the vehicle assembly line. One possibility is different axle ratios since they were built at different times. The other is the lack of "first in , first out" thinking. The differential itself was built ( again) before installation into the housing , BUT the tag was created WHEN it became a drum to drum assembly. This shows by the extremely early casting date on the case of F2 versus the Dec "assembly" date.
     I hope this sheds some light  on this.
     Randy

[KR Convertible]

The case had to be made well in advance of the 6LC assembly tag date which represents 1966, 10th month, third week. Parts like the SPEC case were not made every day of every month so estimating when it might have been cast is not as easy as - for example - a WAR case from a 1962 Galaxie. Low volume parts were cast in batches as needed.

So it might have been a few weeks or a few months before the date on the tag.

I think 6LC should be November.  They didn't use "I" to avoid confusion with "1"

[Bill Collins]

    My SPEC case is currently in my Hertz car but "I" believe the "DIF" letters ( Detroit Iron Foundry) are not on a SPEC case. Later "DOOW_B" , small bearing cases have the MCC ( Michigan Casting Center) logo.
    Randy

I currently have '67 GT500 #1595 for sale and it has a SPEC case with DIF casting. Ford build date was 3/23/67. See photo attached.

[gt350hr]

   Thanks Bill yours makes perfect sense. ''I" wasn't sure about those cars built in '66 as far as when the SPEC case was used. I know SPEC case assemblies were on Jan built cars and in "my" experience , through the end of production. IIRC the "date" returned on cases cast in OCT '67. Kerry ( Sportyworty) has kept excellent records ( and a majority of the research) of actual observed case sates in order to see the "production window" for SPEC cases.
  Randy

[Royce Peterson]

You are correct of course!

The case had to be made well in advance of the 6LC assembly tag date which represents 1966, 10th month, third week. Parts like the SPEC case were not made every day of every month so estimating when it might have been cast is not as easy as - for example - a WAR case from a 1962 Galaxie. Low volume parts were cast in batches as needed.

So it might have been a few weeks or a few months before the date on the tag.

I think 6LC should be November.  They didn't use "I" to avoid confusion with "1"