I'm glad all worked out for you. I had doubts that the clutch packs were bad.

 

Hate to resurrect an old thread but how many miles did it take for the shutter to disappear after adding the new oil?

 

it went away immediately.

I ended up trading in for a 2011 F-150 and guess what - at 29000 miles
its doing the same thing! so I guess I'll be buying more friction modifier.

 

I had oils replaced yesturday. Took it out afterward, did the recommended figure 8's forward and backward and still have some lite chatter today.

Mine is a 2003 F150 KR with 92000 miles

 

I just had my truck in 2 days ago ('05 F-150 with 65k miles) for the slipping / clunking issue and it just had started the chattering vibration from the clutch packs on Monday.

Fluid in the rear end was in pretty bad shape from the clutch pack.

The dealer posted on the repair slip they replaced the clutch packs and per a TSB they lubed the slip yoke as well. Vibrations like a rumble strip were the clutch packs, and the "clunk" on takeoff from an incomplete stop was the slip yoke.

Total cost was $880. I think they see these fairly regularly.