I'm close to biting the bullet on installing my 4:56's and junking the 3:55's.
However......one thing strikes to mind after reading many many threads on this swap.
I have never heard anyone having noise issues or problems, installing the gears in the front diff???
Why is that?
I know the axles are different but, if noise is generated by the gear set manufacturers as some state, Precision quieter than Yukons.....Motives louder than Precisions etc etc etc. Wouldn't there be noise coming from the front diff on a 4X4 as well?
I know that the rear is the main drive on a 4X4 but, the whole assembly in the front diff is turning all the time even with 4X4 not selected. So there still should be noise???
OK there is no load on them at this point but, even when 4X4 is selected I havent read anyone commenting on front diff noise after a 4:56 upgrade??
Just a thought.
Al.

 

I would say you never hear of noise issues of front gears because no one engages them (no load like you said) and drives on pavement with 4wd engaged, therefore never using or hearing them. My rear gears will make noise sometimes but if i put in in neutral it will stop although Im still moving forward and the tires are causing the diff to spin.

 

Manufacturers differ from one another due to the softness and hardness of the metals used. Richmond for example makes a softer compound gear made more towards launching drag cars. Softer metals allow a little give, but tend to be louder going down the highway. Harder gears provide less give and are queiter on the highway.
Some Co.'s make both types(hard&soft) depending on application.

Generally speaking, if gears are installed properly, they shouldn't make any noise and if so, nothing you should hear with your air on or radio on low. It would be a noise that you would need to really focus on. If a mechanic says, all aftermarket gears make noise.... run. They are covering up their botched install.
4:56's need the center pin ground down so DON'T let a mechanic grind down your housing. The carrier pin can be ground down enough to fit those 4:56's without touching your carrier. I'd opt for an Auburn or DTT(if you got $$$) No sense of opening up the rear and installing gears with an open diff or a crappy stock LSD.

 

Quick question about the cross pin in the 91/2" rears Dirty.

I removed my stock LSD and replaced it with a Detroit TruTrac. Best thing so far I've done on this truck.

However, I believe the DTT's do not use a cross pin kin their design?

If this is correct, my installer shouldn't have anything to worry about notching or relieving housings etc, to fit my 4:56's right??
Al.

 

Got Auburn here and just to add comment, there is No grinding required until the Manufacturer change for our Diffs which was after 2005 so pretty sure your good to go for the grinding of Pin and also where the larger 4.56 ring gear come in contact with the housing on later models (plenty of info and pics of subj out there).

BTW No Gear noise here after 7 Months! Good Luck.