Robert I have the TH350C, pre-curser to the 700r4, B&M do this .
I too was looking for a similar solution.
It's a bit pricey though.

They also do an electronic speedo compatible one too.

Last edited by jockbolter50; 04/27/2010 2:39 AM.
1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.