(in other words, a 3.92 has more bottom end than a 3.55, but a 3.55 has more top end than a 3.92)

 

You can see what gearing you have by sliding under the truck near the rear axle and looking at the point where the axle shaft housing meets the hub (far ends near the wheel). There should be a vinyl type sticker that will have your gearing listed. Or you can look at your dealer window sticker if you saved it (always a good idea).

 

Yea my window sticker has my gears listed

 

where can i find a place to buy 4.10 gears?

 

There is also a sticker in the glove box that says what it has.

There are several good places to get gears. Assuming you have the knowledge and tools to put them in. Another option is to find a used one from a salvage yard.

 

don't get richmond gears. They whine and howl. When I had my ranger I got my from a ford dealer. Ask your local dealer how much for the ring and pinion and also do you have posi on your truck right now? If you don't then I would get a posi unit for your truck. They make a hell of a difference and instead of leaving one tire mark you leave 2 plus it helps in rain and snow. I would go with 3.92. Also if I were you I would have the dealer or a speed shop install the gears. There is alot of stuff you have to do to set them up. I had a roomate do mine and another roomate's car. He had done gear swaps in the past on fords but every axle is different.