The truck has 140K miles on it.

There has been no problems until about 15K miles ago when a slow but steadly increasing whine deleloped.

This may be because we started pulling a horse trailer on occasion since that time. The trailer is at the weight limit of the truck.

Again it seems to be getting slowly worse, regardless of load or speed.

What is happening to cause this progression and is a new set of gears the answer?

Thanks for your help.
Cecil

 

it may just be bad bearings.

 

get underneath and see if there is any movement in the pinion. id also pop the cover and take a look. id probably check the pattern too.

 

Pinion seems normal
I'm familiar with chevy c clip rear ends, are the ford rear ends dramatically different?
What is my best choice for a exploded view?

 

if i remember correctly, they are C clip too. its been a few years since ive been in one. i should be able to tell you next week after i get mine apart. is yours a 5.4?

 

I have some farily detailed pics in my gear swap write up at the top of the powertrain page.

oops it's not there anymore, it's in Articles, News and "How-To's"

Gear Swap Write Up 9.75

 

rednck21, It's a 5.4,

efuehrin, The pictures of the teardown are super.

Being that it is a 4X4, does that mean it is a positraction

https://www.f150online.com/forums/me...0-rear-end.jpg

 

It's a limited slip. Ford's limited slip works very well.