Spec Case 9" Rear End 2 Versions for the 1967 GT500

[Scode67FB]

I assume you mean 68 Cougar with R & W code. I can see the early W code cars getting them, but R production started in February 68. Maybe some Mustang 135 cars got SPEC cases? They were built late December 67. About a week or so after the 7L20 and 7L21 no N nodular cases started getting made. Just for reference, my May 11, 1968 Torino GT R code fastback has its original 7M21 case with 31 spline 3.91 trac lock.

I don't know when the non-SPEC Nodular started casting, but I have one dated "7F2."
Does anyone have a pic of a one of these Nodular with no fill plug? Otherwise, I have a hard time believing they exist. The timeframe for their use would be so short and the applications so limited that I don't think Ford would've bothered.

[TLea]

Pretty sure my 65 R code has nodular. Would have been dated prior to cars build (4-65) Has fill plug. Will get pics next time I go to my other building

[430dragpack]

'63-64, Since they are C4AW cases, no "N", SPEC and with "N" until the DOOE bearing size change in May of 1970. 
Tim,
Are you saying '65 R code Shelby or Galaxie?  A 65 Rcode Galaxie does have a no N nodular with both fill plugs(or at least this one does), just looked at an original one couple weeks back, one owner since new. I couldn't get under it far enough to get a picture of the date code.