I have a 03 Supercrew with 3.55 LS gears, I've added a 3.5 spindle system to the front end with 285/16/75 tires. I'm also running Toyers Superchips. I drive approx 500 highway miles a month and the remaining dirt and city. I want the power but dont want to loose to much Gas mileage.

How easy is it to install these?

Thanks

 

With the tire size you have, I wouldn't change gears if you don't want worse milage. Any lower of a gear ratio will give you more power but less milage. I worked on diffs at a ford dealership for a few years and unless you have done them before or can have someone help you who knows what they are doing I wouldn't try them yourself.

 

if you are a decent mechanic and have the right tools(bearing press, dial indicator and micromiteralong with an asortment of sockets and other things) than this job is not that hard just get a manaul and study it it might take you a few tries to get the pinion depth corect and get a good wear patern along with the correct side shims if any of this scares you than have a shop do it, any gear change will afect your mpg but you will regain lost power and maybe get alitttle better mpg in the city but lose on the highway

 

what was your stock tire size? then if you want to get a stock equivlent for your gears u can go to a tire/gear calculator and determine which gears you should go to. Here is the one that I used for my truck. ended up going lower than what was required but I am quite happy with it.
My tires are also a good deal larger than the ones you have now. http://home.comcast.net/~cboug/Tire_Gear_Calculator.htm

 

what was your stock tire size? then if you want to get a stock equivlent for your gears u can go to a tire/gear calculator and determine which gears you should go to. Here is the one that I used for my truck. ended up going lower than what was required but I am quite happy with it.
My tires are also a good deal larger than the ones you have now. http://home.comcast.net/~cboug/Tire_Gear_Calculator.htm
If you had 235/75/16's your stock equivelent is like 3.90 or something. unfortunately that is not really something that is easy to find. if you have an 8.8 and a 2 wheel drive then these are attainable. If not then you can either go with 3.73's or 4.10's

 

cakp-

You'll need 4.10s to put you back near stock, rolling at ~2,000rpms at 70mph in OD. You'll need even more gear if you want performance over highway MPG. Here's what's involved:

www.ring-pinion.com/downloads/yukoninstman.pdf