Diesel 5spd to C4 speedo gear

[fomocoguy]

So my truck, which was a 5 SPD diesel when it rolled off the line in 1984, had a c4 in it when I bought it. Its getting another one, but the speedo wasn't working and I'm trying to figure out if they even had the right gear in it. Here's a pic of what's there:
Is that gear reduction doohicky factory for these? Maybe its an adapter....

 

[adsm08]

That looks right. Ford only had a handful of speedo gears and they weren't specific to any one transmission.

I'm not sure what you mean by "gear reduction doohickey".

 

[fomocoguy]

That looks right. Ford only had a handful of speedo gears and they weren't specific to any one transmission.

I'm not sure what you mean by "gear reduction doohickey".

Oh, I just meant the square aluminum doohickey that is between the cable end and the part that inserts into the trans. I can't recall seeing that part on all the old iron I'm usually working on.

 

[adsm08]

I'm not sure what that is. I'm sure it's not for any sort of gear reduction. That kind of setup would be worthless on a speedometer unless you want a really complex way of making it read incorrectly.

 

[Transman304]

That is a Ratio Adapter that many manufactures used. It will allow a % up or down.
Made for low rear end ratios with short tires. If your speedometer reads too fast with 15 and 45 teeth gears then you need this part. This part will slow down your speedometer reading. Also used to help when change in tire size.

 

[fomocoguy]

So it IS a gear reduction? Now that I've got a 28 inch tall tire back there I may not need it. I'll have to donkey with it once shes up and on the road. Thanks for the input!