As promised here are the sequence settings.

Nothing out of the ordinary. Pretty standard Sony EX cam sequence with 1920×1080 frame size.
But I digress. I believe I really have solved the issue here but I won’t know for certain until the end of the day. I’ve used the method I described before about ONLY selecting the COMPRESSOR NATIVE option for size. This will take the frame size from the sequence itself and the end result looks good and reports only one single frame size of 1920×1080 in MEDIAinfo. In the past I had chosen the 1920×1080 16:9 option in the size dialog box and that definitely is wrong at this point. Don’t THINK for it, let IT think for YOU!
Finally in this case we needed to deliver SD versions of the same spots but in order to make my export method work we had to do this:
1. Create a new sequence.
2. Go to the sequence settings.
3. Load up the DV NTSC 48Khz preset. (this gives us 720×480 native frame size)
4. Make sure to clear your ins and outs on the HD sequence.
5. Drag your HD sequence INTO the new SD sequence.
6. IMPORTANT!!!! DO NOT let the SD sequence auto conform to your HD sequence. When FCP asks you if you want to change the sequence settings to match the clip settings JUST SAY NO!!!
7. Park your edit needle in the middle of the sequence to confirm if the spot is letter boxed. If you don’t want it letterboxed now is your chance to change the size.
8. Render if you wish to see the end result.
9. Go to FILE-EXPORT-USING QUICKTIME CONVERSION and make sure that you choose COMPRESSOR NATIVE for the size. Thats it!
I will post results from cable vision as soon as I have info.
PS: If you don’t have this program already now would be a good time to get it!
https://mediainfo.sourceforge.net/en