Speedo drive identification

[jeffwkirby]

Hi I have a supposedly 1968 A65 Lightning and it is missing a speedo. I have the rear wheel drive, I just need to identify the ratio it uses.
Can anyone assist from these images?

[rhyatt]

The ratio is sometimes marked on the circular brass cover on the other face , pointing inwards face.
Eg 19:10

[jeffwkirby]

Thanks, I had a look and couldn't see anything marked...so, I have gone with chance, I've bought a speedo and cable and we'll see what we get

[rhyatt]

When you look at the other face  the face that looks towards the spokes, there's usually a brass trim plate that, if teased out , holds a felt seal.
Any ratio will be stamped on this brass ring. I'll try and find a picture

Ebay item number 227065705675