The 2nd.gunman is indeed right. After about 1970, all auto and manual sandwich / block / separator plates were the same. Earlier ones from 1966 to 1970 were thicker when used with a manual transmission.
From the seven Ford sixes I've dismantled lately, I've got heaps of spare ones I can send you if your comfortable sending me your details. Normally, air mail is about 5 days. Price is about $ 10 US dollars, which you can donate to Fordsix.com.
PM me. I'm nervous about sending things overseas, so I'd rather send something free than face the embarasment of it not arriving! I did send an EGR blankoff plate a while back to Speedy.
Until my company is up and okay with Uncle Sam, I'm not happy charging anything. I'm still developing parts at the moment using a check cashed in 2004, and I'm not doing anything for anyone until I've squared off that item or I'll get into trouble with Uncle Sam.
Over here they charge about 35 to 60 Kiwi dollars for the C4, Borg Warner 35 and 40 separator plates, but the cost varies depending on who is selling. Since there were over 2 million big 3.3 and 4.1 Aussie Falcon sixes made (some in land fills!), then I don't see why I should be stingy.
I have a US AOD transmission on my Aussie X-flow, and use only US backing plates on mine!