Help Identifying Old SW Speedometer

Can anyone identify this speedometer? I am trying to install it for a friend in a 31 Model A but have no identifying marks or numbers that make sense. The numbers on the back are

860 S
12V F10

If it is usable, I need to find the adapter to hook up to the three prong end.

Thanks

 

Thats a speedo, not a tach

 

Tach?............looks more like a speedo.

M.

 

Special Ed beat me

 

I'm snorting laughing so hard.

 

Never seen a tach with an odometer in it.......... Hehe!!!

 

Oops, it is very late and I have been working on a wiring harness all day!

 

Now you have.

 

Well I'll be damned! Just when you think you've seen it all

 

Its an Argo tach-o-graph. It goes in big trucks/busses and has a little data recorder inside of it with a graph chart. Has a tach, a clock in the center and an odometer. Like a poor mans GPS.