SR77 if you are out of warranty then I would definately go for it! I have little experince with Fords so I would deffer to other long time Ford owners. Ford does not make their own ring and pinon gears so their is no pripritary reason for the 140Wt. THe problem with 140Wt. is that in the cold it is not goiong to do it's job well until the rear end is warm and the fluid is warm.
I would suggest you try searching Timken testing to see what it is. Basicly they spin a bearing and then place a stationary bearing in contact with each other. THe two bearings are seperated by a flim of lubricant. The test can bwe setup in a number of different way. Usualy the size of the wear scar is used to determine pass or fail. Sometimes it is the amount of force that can be carriered. In some cases it is a combination of the two etc...
In this case it is the amount of weight the lubricant is able to seperate before the motor can no longer turn the revolveing bearing/wheel against the stationary bearing. A load of 100lbs carried before failure is better then say 70lbs.
I would suggest you try searching Timken testing to see what it is. Basicly they spin a bearing and then place a stationary bearing in contact with each other. THe two bearings are seperated by a flim of lubricant. The test can bwe setup in a number of different way. Usualy the size of the wear scar is used to determine pass or fail. Sometimes it is the amount of force that can be carriered. In some cases it is a combination of the two etc...
In this case it is the amount of weight the lubricant is able to seperate before the motor can no longer turn the revolveing bearing/wheel against the stationary bearing. A load of 100lbs carried before failure is better then say 70lbs.
