Hello Jerome,
Bob is of course right here.
However, the problem is that for your 1964 car (up to VIN 012466 I mean) the carpet was not grey or charcoal or whatsoever, it was blue!
The Tech Manual is not incorrect here, but incomplete.
The Daimler AG changed carpet colors in August 1965 (i.e. from VIN 012467 on for the 230 SL) when the new W108 chassis was presented for sale.
Your car should originally have (dark to medium) blue carpet, which is NLA for centuries.
There _is_ a somehow replacement available today but only with about 5-6 loops per inch, not 7. The color match is pretty good but not perfect.
Please see Alfred's post in
http://www.sl113.org/forums/index.php?topic=17227.0... then you'll get an idea what the original carpet is/was about.
My two cents,
if you have already charcoal carpet go with it.
If you have to renew your carpet set, go look out for the blue one.
Best,
Achim