Service my 3.73 or upgrade to a 4.10?

[racsan]

it is a bit cold this time of year to wrench on anything. I have a garage but its not heated. Im game for a project when the weather is better. Im near marion ohio, about 7 miles from us 23. Yes, new U-bolts are a good idea, and I admit I didn’t replace mine. Someone on here had a 8.8 4:10 limited slip for sale, think he’s in indiana
EDIT: heres a screenshot, its in the parts for sale section. 2 axles with 4:10’s, decent price, wouldn’t recommend the lock-rite from what some others have told me.

 

[19Walt93]

Just changed the lube on my 2wd 3.73.
The old lube was yucky, but the inside didn’t look too terrible no obvious damage or metal shavings. Teeth look good.

Anyways, I still get like a whirring noise at any/all speeds and prominent when deceleration. it’s not terrible.. but I Figure it needs a new ring/pinion bearing. I have a shop that would probably do that repair for me relatively cheap for what it is.

I can’t even tell how bad it is, I mean I can hear the whirring but it’s not anywhere close to as bad as my Tahoe which absolutely whaled on acceleration whenever I drove it. Does anyone else’s diff make some whirring noise but not enough to make you super concerned? How can I be sure it’s the diff that’s making the noise..? Anything else it could be?


Should I just nut up and find a 4.10 limited slip to upgrade my rear end instead? Only thing that worries me is the MPG hit. How severe is that gonna be ?

If the rear end in your truck makes noise you can hear in the cab it won't last long. Changing with throttle pressure usually indicates a pinion bearing or ring and pinion gear problem.

 

[gaz]

Sheliable,

If you use 4:10's with smaller than 32" tires you will experience a dramatic fuel economy deficit, as much as 4-6 mpg.

 

[Dirtman]

Sheliable,

If you use 4:10's with smaller than 32" tires you will experience a dramatic fuel economy deficit, as much as 4-6 mpg.

That really depends on how the truck is used. On the highway yes it will lower fuel mileage a bit. But in city driving or towing you could actually see an increase in mileage because the engine isn't working as hard at lower speeds. Especially with a 3.0 and an automatic which is gutless at low RPM.

My truck has factory 4.10s and 28" tires, I get 24mpg highway...

 

[19Walt93]

On the hilly highways in New England 4.10's are apt to increase mpg because the trans will be able to stay in overdrive.