I recently purchased a F350 4x4 drw 6.0l diesel tow boss 4.30ls to pull my Trailers West 3hr 8x8 side tack LQ trailer. When I pull it the truck bucks and lunges sometimes SEVERLY! the truck dealer says trailer fault the trailer dealer and manufactur say truck fault all say air bags will solve problem. Can anyone tell me who is right and will it really solve that violent of a buck?  

Is it doing it when the tranny is shifting? I had a 98 Dodge that did that if I did not let up on the gas way before the tranny shifted into higher gears. It turned out to be a problem with the Tow/Haul button. After living thru the nightmare for about 6 months. I went to the dealer with fully loaded LQ trailer in tow, loaded up the service manager and the tranny mechanic and drove over South Mt with their computer attached to the truck brain. An hour later, my "captives"  had all the info they needed at the exact moment it was doing it and ordered the "correct" part. That totally fixed my problem after the 5th time in the shop for the same problem.

you wrote:When I pull it the truck bucks and lunges sometimes SEVERLY

It's a automatic and very smooth so I'm not sure if it is sifting and I too have had "captives" from the dealer and they begged me to make it stop. They still say Trailer problem, grainery near me weight it and said tongue weight was 33% with nothing in the LQ(water etc) but TW swears it was less than 25% when it left. My big concern is if I put airbags and fill the trailer for a upcoming trip will I be ok of will my horses refuse to ever get in it again!

If you haven't done so yet, post your question on these forms. You  will get some straight answers from people that know. All too often the Stealership (both truck and trailer) try to blow you off, or flat out just don't have qualified people woking there who can solve the problem

http://www.ford-trucks.com/forums/showthread.php?t=502914

http://forums.thedieselstop.com/ubbthreads/postlist.php?Cat=0&Board=2003Drivetrain1

We just got done dealing with a similar issue. It involved a 2006 Ford truck and a living quarters trailer – shaking pretty bad (jerking back and forth). It was worse when you were slowing down and nearing a stop. The customer was positive that it was the fault of the trailer. We tried several things on the trailer (to no avail) and then called Ford.

In this case, it took several calls and a good Ford dealer to physically inspect the truck, but it ended up being an easy fix. The Ford dealer replaced a chip in the truck that synchronizes acceleration and braking, and the problem was solved.

I can’t say that this is the case with your set up, but it is worth checking.

Hello n2collies and welcome to the forum. Everyone has come up with good stuff so far and I'll attemp to add to the solution. If none of the "idiot lights" on your instrument panel are coming on when the problem is happening, that's a good thing. If any lights are coming on, the computer should be storing a code for the problem, but I don't think that is your problem.

If I were solving the problem, I would want you to take me for a ride in your rig and let me ride in the trailer. The first thing I want to know is if the trailer brakes are engaging intermitently to cause the jerking and bucking? If the brakes are coming on and going off rapidly, I'm going to be staring at your truck as the guilty party.

I think you've already elminated the trailer as the problem by towing the trailer with your trade in recently. Someone already mentioned the "stealership" as trying to avoid the problem and they will. My wife hates "stealerships" so much, that I can't let her take our truck in for service any more. The last time she was there was about a year ago and it got ugly, but she got results. Anyway, I think the truck is the problem and you need to stay on the dealer to make them fix it.  Happy trails.

I have a F350 Lariet Superduty and I also manufacture living quarters.

I haul all brands and sizes of trailers converted and not, I have had no problems what so ever with the ford. I also just purchased a Bully Dog power pup, WOW What a major gain in Power, torque and mileage. 

I've seen some 04 Fords with a vibration problem similar to jerking. It was solved by Ford service centers by shimming leaf springs to change the angle of the drive shaft connecting to the pinion shaft. But making it ride better loaded made it ride worse empty. On some F450/550's with jerking problems, Ford added a rear axle tracking bar.

When I talked to some of the Ford engineers this spring while at the 07 Sport Trac media launch, they denied knowing anything about it. Firing too many good engineers over the 2003 Power Stroke problem is still plaging Ford.

Next week I'll be in Oregon driving the 2007 Expedition EL (longer) I'll see what the latest fix is. Might even find out more on the 6.4L PS. The new Expedition will be rated to tow over 10,000 lbs. But I still morn the death of Excursion diesel.