Ebay actually has the Yukon 4.56s on there for cheaper than the actual website sells them for. Just not the overhaul kits though..

I'm going 4.56s in Spring when I get my 35s here hopefully soon. I hate these 33x12.50s with stock 3.55 gearing..

Guess I'll need a 37t gear to have my speedo corrected. They hard to install?

 

They're extremely easy to install. Unplug the plug from the speedo housing on the transfer case and remove the "Y" clamp thing bolt (you'll see what I'm talking about when you crawl under there). Lift up the "Y" clamp thing, set the bolt and "Y" clamp thing aside, and carefully pull the speedo housing straight out of the transfer case.

Grab the plastic toothed gear on the housing and pull it out. Push the new one in till it clicks.

Reinstall (and don't forget to plug the wire harness thing back in).

Now there are marking on the side of the speedo housing thing you'll have in your hand when you remove it from the transfer case. It'll have marking on the side for what groove to have the "Y" clamp thing in based on your tooth count. It'll be like 28-33, 34-38, 39-45. Make sure you use the right groove based on your new tooth count. It'll make sense when you take it out. The speedo housing will be rotated based on these grooves.

If someone can explain it better than me please chime in.

And how do you like the 1.7 rockers? Can you tell a difference?

 

^Thanks for the big write up man.

And they make it run smoother. Can't really tell too much of a difference like everyone claims on here but they help with the other supporting mods. I can hear them slightly clicking in there, but rockers are supposed to have a slight tick.

Probably if I had the gears to match my tires and then installed them, I would probably notice more.

 

To follow up on this thread...

So this weekend I installed the posi-lok (perm-lok) - pretty straight forward - same one shown above (non-cable unit). I also installed a new shift fork. It was more of a pain removing all the vacuum lines and finding where it connected into the system (so I could plug it) than it was to actually install the unit. Now the collar is permanently slid over connecting the two axles to act as one. So essentially/functionally my two-piece long side axle shaft is a one-piece axle.

I then replaced the vacuum plug thing on the transfer case with an electrical plug similar as in the picture above (from a 97 - 06 Jeep TJ). The electrical plug from the axle unit (at the CAD) plugged right into it, although I had to add about five feet of wiring (two wires) to have the plug reach from the front of the truck (where it plugged into the CAD unit on the axle) back to the transfer case (leave some slack for axle movement). But it works! Shift into 4WD and the 4WD dash light lights up; shift into 2WD and it goes out. I'm pleased with it. Let me know if you're interested and I can get you the part number for the electrical plug.

Edit: It's an Airtex 1S2041 http://www.rockauto.com/dbphp/x,cata...LS_1S2041.html

I wasn't having an issue with the vacuum actuated system (other than it didn't engage right away) - I just wanted to remove that possibility and make it fool-proof.

Oh; and with the 285 tires and 4.10 gears I'm getting around 12 mpg. We'll see if having the front axle locked how it affects my MPG (it doesn't really).

 

I'd be interested to see if there is an MPG difference with a permanently engaged CAD.
This should be the same as a non-CAD axle without free-wheeling hubs.

FWH are supposed to save MPG, but with a truck this size, is that extra spinning mass really going to make that much difference?

 

I have the equivalent of a permanently engaged cad. I have a solid shaft

Im getting dang near 13 mpg mixed. But I attribute it more to the 4.10 gears then anything else.

 

I'm sniffing at 14mpg on 265/75/16's with 3.55's.

I have a PosiLok on my list of stuff to do, but if there aren't going to be any real downsides other than not gaining 2L, the above seems like a good option.

 

I wanted to go the foolproof route; hence the full-time Posi-lock (Perm-Lok) engagement. I figure if Jeep decided to go the solid one-piece axle shaft route on their early Grand Cherokees and TJs (I have both) it's good enough for me. And it's a lot cheaper and easier to install than buying a one-piece axle. I've never heard of anyone breaking the sliding collar on their axle before either, so I figured there's not a strength issue there.

 

Typically (other 4x4's) the axles are one piece... for these, FWH's where an aftermarket item to save gas by lessening the spinning mass.

How much was the one piece axle?... any other components need changing?
Drop all the CAD guts and put a flat cover plate on the opening?

 

A one-piece axle and CAD delete kit is $225 and it comes complete with axle, block-off plate, and seal:

http://www.emsoffroad.com/store/inde...roducts_id=350

There's a seal you have to replace inside the tube which looks like a PIA to replace (click on link and read the instructions) among the other things you need to do to replace the axle shaft. Not that I've done an exhaustive search, but I've never seen another one-piece axle for our Dodge trucks for sale. EMS sells a whole kit to replace the unit bearing hubs with real locking hubs, and comes with new outer axle stubs. Looks like a nice kit. It's like $800 (but it doesn't come with the one-piece long axle shaft). They also don't sell a replacement short-side inner axle shaft.

The Posi-lok "Perm-lok" (what I put on my truck) is $83

http://www.4x4posi-lok.com/app_dodge.html part #1100

And since my truck has just over 200,000 miles on it I went ahead and replaced the fork (another $40 - part #100 or $29 from Summit Racing). The factory fork still looked good when I took it off, but I had ordered the new fork when I ordered the Posi-lok (Perm-lok) just to be on the safe side when I took the old unit off (I didn't know what I'd find, so I figured since it wasn't expensive to have a new one to put back in I'd just go ahead and get one).

The vacuum switch on the transfer case I swapped with an Airtex switch part # 1S2041 ($17.50) and it works just as it should after I extended the wiring from the axle plug to the transfer case (4WD light comes on when shifted into 4WD; turns off when back into 2WD). It's a fairly easy swap and to extend/run the wires, and you'll never be guessing if you have it in 4WD or not because the dash light will be lit when you do. I would recommend you swap out the switch if you did either the solid one-piece axle or the Posi-lok (Perm-lok).

http://www.rockauto.com/dbphp/x,cata...LS_1S2041.html

So you're looking at $225 vs. $83 (and a lot less work going the $83 route). And either route you go add another $17 for a plug and a few feet of wire and a couple butt connectors. I also spent a few dollars on some 3/8" black wiring cover/loom/conduit/whatever-you-want-to-call-it to make it all look pretty under the truck (because I'm like that).