Speedo drive gear advice please.

1991 200 Tdi 90, 1.22 transfer box off a Disco, 235/85/16 rubber. Speedo reads around 10% low.

Its time for me to replace the speedo cable, while doing this it makes sense to change the original Disco drive gear to bring the speedo readings back to somewhere near accurate.
I have searched all over this and other forums and ended up being more confused than when I started looking, anyone got any advice as to which colour drive gear I should be (trying to) fitting in the transfer box. Pretty please.
@jamesmartin perhaps??

frog hopper said:

1991 200 Tdi 90, 1.22 transfer box off a Disco, 235/85/16 rubber. Speedo reads around 10% low.

Its time for me to replace the speedo cable, while doing this it makes sense to change the original Disco drive gear to bring the speedo readings back to somewhere near accurate.
I have searched all over this and other forums and ended up being more confused than when I started looking, anyone got any advice as to which colour drive gear I should be (trying to) fitting in the transfer box. Pretty please.
@jamesmartin perhaps??

Click to expand...

blue with the large tyre frc3310

jamesmartin said:

blue with the large tyre frc3310

Click to expand...

Thank you VERY much James, I was hoping you would pick this up.
I can place an order now for this and the rest of my 90's shopping list.

So fitted the new drive gear and speedo cable today.
Ended up removing the handbrake backplate for access to the drive gear housing, much to my surprise it came out quite easily, fitted new blue gear and replaced the cable. I had left it overnight with a plastic bag taped over one end with some oil in and raised up to make sure it was well lubed before fitting.
Everything back together, gps set up on windscreen, off up the road for a test. Nothing at all.
I hadn't fully located the instrument end, so simple fix. (that makes a change)
So, speedo vs gps.
30 mph at an indicated 31
40 mph at an indicated 42
50 ------------------------- 53
I can see a pattern developing here. ---------------- so all very good and simple.
Big thanks to @jamesmartin for suggesting the right part.