TR6 TR6 overdrive speedo pinion

[Airfix]

Installed a J type overdrive a couple of months ago, angle drive cable won't fit into the O/drive speedo pinion shaft.
I know this means a Volvo part is installed, question is what colour is a Triumph J type speedo pinion gear? mine is blue and it's plastic. How many teeth on the Triumph one?
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[71tr]

Airfix,
I'm adding a volvo J type overdrive to my TR6 four speed. I sourced an angle drive from one of the big vendors and it's cable slides into and works with the volvo's speedo pinion. The volvo's pinion gear is a dark brown color and has 18 teeth.

My understanding from discussions with John Esposito at Quantum Mechanics to get an accurate TR6 speedo readout you must replace the guts of the volvo overdrive with appropriate triumph hardware. This involves two items; 8-start speedo drive gear which is internal to the overdrive unit and a 20-tooth speedo pinion gear which connects to your angle drive.

How many teeth does your blue pinion have? Not sure why you are having problems with the cable, they seem to be universal?

 

[Airfix]

Found another angle drive which fits into the speedo pinion gear shaft.
Quite a difference on the male end, slips in easy.
Anybody have any idea why there is difference in size? I picked it out from the used box at one of my local suppliers, would like to find out where the smaller size one comes from so that I can order a new spare.
Turns out that the blue 18 tooth gear must be right as my speedo odometer is accurate although I did calibrate the needle as it always read 50 when doing 60 (before O/D install also) Great instructions on the web, all I had to do was remove it, take the back off, turn the drum and hold with the needle at 50 them move the needle to 60 while still holding the drum. Checked it out and it's now spot on at 40, 50 and 60. https://mywebpages.comcast.net/rhodes/speedo.pdf