Have a 05 4.6l 4x4 with the 3.55's OpenDiff and have 35" mtz's.. And boy is my truck not happy on highways! I have been looking for a used 3.75LS for the front and back. Been to all my local junkyard and im always looking on ebay and no suck luck.. Now i know alot of you are prob asking just not just rebuild mine , the answer is that it just costs 2 damn much... So im asking for some help from u guys .. Anyone know where i can find them for a decent price?

 

3.75??? dont you mean a 3.73??

 

If you aren't happy with 3.55 then 3.73 will be a disappointment...the difference will hardly be noticeable. And if you are turning 35's, then you I doubt you will notice an improvement at all.

The 4x4 gurus will chime in here, but IMHO with 35's you should be looking at 4.56 or even 4.88 for more oomph. There are many of us who 4.10s on street-sized tires, myself included (I've got 285/60R18 tires, about 31.5 inches).

Here's some good recent posts for ya:
https://www.f150online.com/forums/sh...d.php?t=263266
https://www.f150online.com/forums/sh...d.php?t=263323

 

if what ur sayin is true , then i will not be doing anything at all because i looked into prices of gears and what not and thats just out of my budget. Would a programer and intake help out any , i could wait for the next group buy on the 2.. I just hate how my truck has to downshift 1 or 2 gears to get up a slight incline..



Also yes i ment 3.73's

 

I was having the same problem so I went to a salvage yard and inquired about it. They said they would give me the entire rearend for $700. That is pretty ridiculous when I can get my truck (both differentials) regeared for under $1000. I have since began working at that same salvage yard and I will say that you are going to have a hard time finding just the internals. They are going to want to sell you the whole rearend (axleshafts, calipers, rotors, etc.). IMO, it is just not worth it to buy an entire *used* rearend when for just a little more money, you can reagear to 4.56s and make your truck much happier. The only drawback to regearing is that you would keep your open diff. I recently blew my open diff and replaced it with a Ford LS. I will say that that thing is just about useless. I do notice a bit of a difference, for instance now I can do donuts where I previously couldn't. However, in the mud, more often than not it does not lock up at all. Don't get your heart set on that LS. Save up some money and buy a better aftermarket unit.