Okay I swapped out the 2.73 for the 3.42's. But I haven't put in the speedo recal gears because getting the 2nd one off the tail shaft looked too tough at the time. And both stock gears are red, which I thought was weird looking. But I could easily swap out the other one. So here's my question, what if I did just that, swap out only the first gear? Would it even fit, would it change anything otherwise?

My bro and I paced one night and if I am going 50mph, my speedo says 57, so that's like 14-17% off. (His tires are shorter than stock)

 

If you already have one of the gears you need, then no you don't need to change it.

 

What do you mean? I have them but I haven't installed them. I was just wondering what would happen if I swapped out the easy one only.

 

If the gear you have now is the same as the one you're going to put on, you don't need to change it.

 

If the drive gear is still the stock red 17 tooth one and your running 245/50/16's just get a 45 tooth driven gear. That will get you within a mph or two to dead on @ 60mph.