"but on the highway sucked big *****"

That's a really good tech explanation, but try again

 

they dont make 3.55s for the 7.5

 

If your talking about me I have a built 8.8 for a rear end.

 

Don't install them yourself. Judging by the fact that you asked if they are easy toinstall, im assuming you havent done it before. If this is the case, don't try. There are too many things that can be messed up if you dont do it right, so just get them professionally installed.

 

hoe about singleports are done making power at about 4800rpm's so 4.10's are a waste of gas and money on stock to bolt-on singleports. they don't make power like your DOHC 4.6. they make power in the midrange where 3.73's are perfectly fine.

also 3.45's are a damn nice gear for singleports

 

Depends on what he is using it for. For daily driver/highway use 4.10's are perfect; bear in mind this is from my own personal experience as we also have a V6 in our "stable" in addition to the DOHC

 

But what year is it? This guys car is a singleport, so its different from the 99-04s.

94-98=3.73s
99-04=4.10s

 

makes sence then[8D]

 

I even have a I-4 Ranger that I would prefer to have 4.10's in, instead of the 3.73's that come stock in it. So what if, as cobra232 posted, singleports are done making power at 4800 rpm? On a daily driven vehicle, on or off the highway, how much time at 5000+ rpm anyway. The V6 auto we have, with 4.10's, doesn't hit 3000 rpm on the highway until about 80 mph. That's hardly overtaxing the engine by any stretch of the imagination.

 

gearing multiplies the torque of the engine to the wheels. if you don't have a large rpm band to work with (like say if the power drops off hard at 4800), then it's not super wise to go with the lowest gears possible (4.10's) because you're not going to be able to use the torque that you have as long as you would with taller gears (3.73's). now if you're able to wind it up higher and the power doesn't drop off so early (like a split port), then the more gear the better.

gearing is hard to explain...sorry if that didn't make a whole lot of sense.