Thought I'd repost this over here since it seems more appropriate....

Ok, as indicated below I own a 2011 F-250, FX-4, 156" WB... I came across this TSB which addresses F-250 Rear Sag. The TSB directs the replacement of the drive shaft. I stopped by my local Ford dealer and verified that an F-350, 4x4, 156" WB, 6.7L uses the same drive shaft. The TSB replaces the 2" blocks on the rear axle with the 4" blocks that come on the F-350. If the same drive shaft is used, why would it be required to replace the drive shaft for the performance of this TSB?

Rework.....

I was under the truck this morning and noticed that the driver side block was about ready to fall out. I had this TSB performed at a Ford Dealer and it would appear that the u-bolts were never properly torqued. I had noticed some noise after the install but it was intermittent at best and I was unable to locate it. Thankfully this morning I found the problem before it found me.

What is the proper torque spec for these bolts? Thanks in advance!

Installation

NOTICE: Final tightening of the shackle-to-rear bracket bolt must be done with the suspension at curb height or damage to the bushing may occur.

Position the rear spring and install the shackle-to-rear bracket bolt and flagnut until snug. Do not tighten the bolt at this time.
NOTICE: Final tightening of the spring-to-front bracket bolt must be done with the suspension at curb height or damage to the bushing may occur.

Install the spring-to-front bracket bolt and nut until snug. Do not tighten the bolt at this time.
NOTICE: Final tightening of the U-bolt nuts must be done with the suspension at curb height or incorrect clamp load may occur.

Position the bottom cap and install the U-bolts and nuts, align the U-bolts so they are as vertical as possible, and tighten until snug. Do not fully tighten the nuts at this time.
Position the parking brake cable and the parking brake cable bracket and install the nut. (LH side only).
Tighten to 28 Nm (21 lb-ft).
Clip the wheel speed sensor harness to the U-bolts.
With the suspension at curb height, tighten the new shackle-to-rear bracket bolt to 225 Nm (166 lb-ft).
With the suspension at curb height, tighten the new spring-to-front bracket bolt to 515 Nm (380 lb-ft).
With the suspension at curb height, tighten the new U-bolt nuts evenly in a cross-type pattern in 4 stages.
Stage 1: Tighten to 65 Nm (48 lb-ft).
Stage 2: Tighten to 130 Nm (96 lb-ft).
Stage 3: Tighten to 200 Nm (148 lb-ft).
Stage 4: Tighten to 265 Nm (195 lb-ft).

Thank you very much! I was going to throw some pics up but the ones I took exceed the file size limit.

I am going to assume "curb height" means vehicle weight is on the suspension(no jack on frame or axle)....

Re-aligned both blocks and re-torqued properly(both sides) to 195 ft-lbs.

Vince, as I think more about this is there any concern that the axle is no longer aligned with the suspension? The driver side u-bolts were fairly loose. I measured the distance from the axle hub to the lower u-bolt bracket on both sides. They were not the same.

suprdtydvr said:

Vince, as I think more about this is there any concern that the axle is no longer aligned with the suspension? The driver side u-bolts were fairly loose. I measured the distance from the axle hub to the lower u-bolt bracket on both sides. They were not the same.

Click to expand...

Nah, there's locator pins that put them at the right spot. After you drive a bit, retorque them again. Its not unusual for them to loosen up after the springs settle.