1965 Convertible top cables specs

[irobbie]

I have a 1965 Convertible with a good roof but badly in need of new side tension cables. The current ones are so stretched that I can easily slide my whole arm in between the top and the window. I have purchased a set from a US supplier marked "1965-1970 GM "C" Body Side Tension Cables but my upholstery man says they are too long.  Imported a second set from another supplier and they are the same length - surprise, surprise. Does someone have the correct specs for the length of these cables? Or maybe "C" Body cables are incorrect? Or is there a particular installation process that has to be followed? As usual any assistance greatly appreciated.
Cheers, Ian. Member# 20080
1940 S62 Coupe
1965 DeVille Convertible
2000 Seville STS RHD

[prodjay10]

Does it have springs? You want a little tension, not much. Just enough to keep the sides of the top from flapping when cruising.

[35-709]

This thread, and the one titled "Scissor Top", both go back to March 2021.  "irobbie" hasn't been back here since (maybe because he didn't get any answers back then).  "Mrmatthew" who posted Scissor Top visited earlier this month but has not posted to his (now old) thread --- also probably because no one answered his original query