Technical 1940 Ford Speedometer Repair/Replace

I need to repair the speedo in my recently acquired 40 Ford Standard. Seller told me that it is the issue is the gauge, not cable or trans connection.

Car is 6V, V8 flathead and although I have a plan to modify and convert to 12v, I want to drive as is for a while while I collect parts.

I found an earlier thread that talked about newer models that will fit and work, but I cannot find it again.

Any ideas?

 

I have mine redone and converted to 12V by Lee Kelly in Idaho-has done 12 or 13 for me--excellent work

 

Lee is still around??
Knew him back in my Forty Ford days he is the greatest unknown builder.

 

Lee is still around and doing instrument repair--does excellent work-spoke with him yesterday.