I need to put a request out to the F350 crowd to see if anyone with an extended cab, long box, wheelbase 158", is willing to get me the engineering number off their midship bearing spacer. I saw one today at work, measured it, but didn't get any numbers off of it. It is 1 3/8th" longer then the one I have on my F250, and I need to get one. The dealer says I have two to pick from, and I have no way of knowing which one I need. The truck I saw at work is gone, and I'm not sure if I can get it back to get a number off of it. All I know is that it was 7 1/4" tall, as compared to the one on my F250 which is 5 7/8" tall. The reason for this was the the rear block change I made, and the drive away vibration I'm now experiencing. Any help would be great.
Alan

 

I think you should not need the part you are asking about. I also made the block change and did not have to change the carrier. Did you install the correct blocks? Tapered on non-tapered? These are dependent on wheelbase. I noticed from other threads researched before I did my change that the vibration is caused by this. Do a search on blocks maybe. Good luck.

 

I do have the correct non-taped blocks installed, and other then a slight vibration that feels like axle wrap, the truck is fine. However, I know for a fact that the midship bearing mount on that F350 WAS different then what's on my truck now, and that's what's bothering me. It was at least an 1 1/2" or and 1 3/8" taller then mine, and I'm hoping I'm not doing damage to my driveline. As a side note, there aren't any engineering numbers on it that I could see, at least in the installed position, I slid under a truck in our parking lot at work.
Alan

 

I just noticed there is another thread going on about this same issue. You might want to check it out. Much more info than I can give.

Ted

 

Why don't you just get a shim kit. It's a lot easier to add shims to your existing carrier bearing than having to disconnect the drive shaft to swap it out. SuperLift makes the kit that I used when I swapped my 0" blocks for 3" blocks. It's only like 34 bones and it took care of the vibrations entirely.

 

I plan to do this install tonight. If I happen to get the right part at the dealer on Monday, I'll publish the correct part number for anyone who needs it. I'm taking a trip with the truck with a full load of camping gear and my boat in tow, so I want to make sure I don't hurt my truck next week. Nice pic by the way, have you noticed any vibrations at all?
Alan

 

xc if you get the different spacer be prepared for lots of work to replace it. The bolts that attach it to the frame aren't accessible without unbolting the body mounts and raising the cab. Or maybe it was just that way on the one I did. Hopefully

 

I had two types of vibrations after my 4" lift.
The first was a high-pitched vibration that occured when taking off from a dead stop with anything more than a gentle throttle. That's the driveshaft u-joints that are at too high of an angle in relation to each other. This vibration was at it's worst when the bed and the fuel tank were empty. It would shake my foot off of the clutch pedal it was so bad. Through about 4 tries adding shims, I found that adding 1 3/4" total eliminated all driveshaft angle vibrations. You shouldn't have to add that much to yours because these problems are usually at their worst on short wheelbase vehicles. Reg cab long bed is the shortest you can get an F250/350 and the driveshaft angle is pretty steep compared to your extended cab long bed.

The second is axle wrap. The torque applied to the rear axle is such that the springs bend in a "s" shape back and forth. I still have that but only when I take off fast in "L" or in "R". The 3" blocks made this vibration worse than with no blocks because the axle now has more leverage on the springs. I can tell the difference between the two because that is a lot lower frequency vibration. (Maybe 1 to 2 vibrations per second.) There are two ways to fix that; traction bars or a spring pack. I don't like the looks of traction bars so I am probably going to get a 3" lift spring pack that will replace the existing springs and get rid of the 3" blocks.

Anyhow, after I installed the shim kit, there are no more driveshaft angle vibrations whatsoever. The kit comes with almost everything you need; 2" worth of shims, two longer grade 8 bolts (The factory bolts are only grade 5.), and 2 washers. The only thing that you will need is some loctite. (And a torque wrench.) Another way to have eliminated the problem would have been a one-piece driveshaft, but it's also more work and money.