Stop in for a cup of coffee

@Icetech speaks not with fork-ed tongue. The 9 is the 9" ring gear diameter. The 25 is the last two digits of the gear ratio and it's missing the characters before the 25, OR they are stamped lightly and the dirt and rust covers them up. However, I know from experience that there is only ONE 9" ratio that ends in "25" and that's the 3.25 ratio, so that's what you have there. IF the tag reads "3L25" for example, that means you have a 3.25:1 ratio with a locking or limited slip differential. That's what the "L" means. I would maybe remove the tag and gently clean it and even look on the back side. You might can see something there. But according to the tag, you at least have a 3.25 ratio, which is pretty decent.
Decoding ford #'s is kinda weird.. they just randomly leave **** off the tag :)

If the rear is cheap it's a good starting point.. 9" tru-tracks (i think that's the name?) are pretty cheap....