Rear differential going out

[Ristin]

Edited for clarity:

2000 Eddie Bauer 5.4l 4x4 154k miles

I have rear diff noise (howling around 35mph) and glitter stuck to the fill plug magnet.

Thinking about re-gearing truck to 4.56 or 4.88 with True Trac's. I'll eventually go to an LT285/75 R17 tire.

This rig is not my daily and rarely sees long trips or freeway driving, but I do tow a boat or travel trailer locally.

This chart shows RPM at 60 mph with different gearing configs. 1st config group is the current stock setup. 2nd group is stock gearing with larger tires. 3rd config is bigger tires with 4.56, 4th config with 4.88 and last is 4.88 with stock tires.

I'm leaning toward 4.56 but I welcome input from folks that have already re-geared.

Config.	MPH	Tire Diameter	Rear Gear Ratio	Trans gear ratio	RPM	Difference
LT265/70R-17 4th	60​	31.6​	3.55​	0.71	1608.0​
LT265/70R-17 3rd	60​	31.6​	3.55​	1	2264.8​
LT285/75 R17 4th		33.8​	3.55​	0.71	1503.4​	-104.7​
LT285/75 R17 3rd		33.8​	3.55​	1	2117.4​	-147.4​
LT285/75 R17 4th		33.8​	4.56​	0.71	1931.1​	323.1​
LT285/75 R17 3rd		33.8​	4.56​	1	2719.8​	455.0​
LT285/75 R17 4th		33.8​	4.88​	0.71	2066.6​	458.6​
LT285/75 R17 3rd		33.8​	4.88​	1	2910.7​	645.9​
LT265/70R-17 4th		31.6​	4.88​	0.71	2210.5​	602.4​
LT265/70R-17 3rd		31.6​	4.88​	1	3113.3​	848.5​

 

[Fastcar]

You lost me. On one hand you'd sell it for 1K, Then you like it and would toss around 5K into it for gearing. I'm sure more than a few of us have pretty much thought of doing the same or have done the same. Welcome to the endless money pit. Like any project it will take on a life of it's own. I've run 4:56's on a street racer, of course the tires were shorter. One thing I remember vividly was driving from point a to b and it was a *****, too many rpm. I was looking for an overdrive unit to slap on it. I'd keep it for a toy build it and buy something else to tow with.