I own a Metuchen built, 1965 K GT Fastback, which underwent a complete restoration. Car was actually built around the 23rd of June 1965.
Delivered to Archway Ford in Baltimore.
During the restoration I posed this same transmission question on the old hipomustang site.
Lots of opinions and good information were provided to the thread, even by some of those who also responded to your thread.
Relied on the kindness of strangers for certain parts.
Bought my original radiator from Charles Turner around 12 years ago.
Also, Change Levels 7/8 are relevant to the drivetrain for cars from these dates.
I believe that Dearborn and Metuchen radiators are different from San Jose.
My VIN stamped transmission is a HEH-T.
There are a lot of unique traits of Metuchen built cars. In fact, the "K" in the transmission stamped VIN is backwards.
Did you find your buck tag, a metal stamped tag with wavy edges? Only Metuchen built cars have one.
It has an identifying list of car verification info and car options.
For 1965, the buck tag should have been located on the passenger-side fender apron under the hood.
You should be able to see the imprint left by the tag due to moisture trapped underneath the tag, if the area has not been disturbed or exposed for a long period of time.
I also have the original broadcast sheet for my kar.
Although k-code drivetrains did have a number of specialized k-code parts, some are just regular Mustang parts.
IF you are really into drivetrain originality, get yourself a copy of a very important reference manual: Mustang & Ford Small Block V8 1962 - 1969 written by Bob Mannel.
Contact me with any other questions that you may have.
Have fun resurrecting the kar.
David Kaplan