where to buy a new speedometer gear?

[1991 Blue danger ranger]

I'm planning on putting on a set of 31's by the winter (current set are almost worn, got 3 tires free and bought a random other one lol) and I've been looking into recalibrating my speedometer as it will obviously be pretty far off (28.5" ish diameter currently and going to a 31" diameter). I'm just not sure where to find a replacement gear? heard they are colour coded based on tooth count. TIA

 

[rusty ol ranger]

They are color coded.

I believe jegs and summit carry them. Pry others too...just google "ford speedo drive gear"

There is also calculators out there online to find out which gear you need for what tires

 

[Curious Hound]

Jeff's Bronco graveyard sells them.