You want to get Timkens as they are the best quality and is the OEM ones that ford uses but at half the cost of going thru Ford. Rock auto or Amazon has seemed to have the best prices.
http://www.amazon.com/Timken-515020...&newCar=1&s=automotive&vehicleType=automotive
Now is also a great time for your friend to replace the ball joints as well. I honestly would do it if they have a ton of miles on them even if they seem ok. But that just me. I do things at set mileage rather than waiting for them to completely fail and possibly do other damage or wear to parts that are far more costly to fix replace. It also allows me to do it on my schedule rather than fate's timing. For those the very best I have found that fit stock are made by XRF. They also happen to be the lowest cost and yet in my experience as well as a number of others have proven much better than moog which has seemed to go down hill over the last 5yrs or so.
Instructions for both unit and ball joints:
http://www.superdutypsd.com/ball_joint_article.php'
On the unit bearings I have had some come with the mounting studs and others not. Make sure to ask or just pick up 2 sets ( 4 each unit bearing) and return them if they end up coming with them.
BTW going forward you can actually grease these nonserviceable unit bearings that are suppose to be ungreasable. You pull the anti lock break sensor from its port and find a grease fitting that can friction fit that hole and grease while slowly turning the unit until you feel it start to resist a bit when you are turning it. Do not force it in there as it will just blow out thru the seals if you go over board. After new install grease them once a year IMO seems to be good and what I do now. If you do a few searches you will see all kinds of info and pic showing broken apart unit bearings so you can see the grease is going right where its needed and how dried out and devoid of any grease the bearings are on failed units.
You should also grease the needle bearings which are in the rear of the unit bearing housing.
http://www.guzzle7pt3.com/nblube.php
One of the suspected issues with the decreased duty life of the unit bearings in the trucks with front ABS is the abs port itself is not a tight seal and allow them to dry out over time. You will be surprised how much grease it takes to refill one up if its an older unit that has never been done.
here is a some pic I posted up of breakdown of the unit bearing
Unit Bearing Dissection
Anyways hopefully that will greatly reduce the freq of unit bearing swap out. Nothing it going to prevent the wear and tear large tires and hard rough driving will put on bearings meant for small tires though. Just take a look at the F550 units versus the 250/350 and it become clear.
