According to the engineer post below, the 2 piece is for safety in accidents to avoid the shaft plunging through the cab into your body, to avoid the fuel tanks (both at full jounce and accidents), and ride quality.

Both my F150 and my Bullitt have the 3.73s with the Bullitt having the GT500KR Traction-Lok diff and the increased throttle response. I have zero clunk whether in city, stop & go freeway traffic, or on a rough dirt road, unless I drive like a douchebag.
The 1/4 mile dirt road into my ranch is extremely bumpy with large holes and I take it slow in 1st gear - where clunk would be easiest to get. But I disengage the clutch a millisecond before I let off the accelerator and tap the brakes. The only noise I occasionally hear are the clutch packs working due to the uneven large holes.
I never realized I had such superior driving skills over other Mustang drivers. lol

 

Perhaps the gears in your diff aren't set properly.

 

I would take most engineers statements with their understanding to be correct. I worked with engineers for over 36 years as I am one. In a room or meeting almost always each had a different conclusion on solving a problem or why a design is the way it is. Again the GT500 is a one piece so I guess in a rear collision their safety would be compromised. I believe the two piece is more for NVH among other manufacturing overhead reasons. Your are right about you being able to shift with zero clunk but I would be surprised if you can do it 100% of the time and never get the noise that most are complaining about.

 

My hunch would be that the carbon fiber would shatter. Judging from F1 incidents. But I'm just guessing you prob would know better.

Well I double clutch on all downshifts out of habit so my right foot is as well trained as my left foot to take up slack in the drive train or let it go before a clunk occurs.

 

+1 on the double clutch and I agree that the CF DS would turn into a broom like mass.

 

Got it fixed!

From further testing, I was starting to get confident that it wasn't the gears or the driveshaft because I was able to get a delay between starting moving and the noise, which should take up any slack that would've produced the noise.

It ended up being the UCA. Mine's adjustable and one of the jam nuts had worked itself loose. Pretty quick fix. Thanks for the help guys.

 

Mine had a small clunk too, I had my dealer check it and they said nothing to worry about, weird thing is it seems like its going away.

 

Thank you for the updates, guys!

Deysha

 

Guess it was 'B' after all.

<B) Assuming its not something major like suspension dragging the ground >

 

I have manuals and automatics all my life. Cars with One piece DS and two piece DS it does not matter. Drive line slack is in all of them. The auto mask it the manuals make it loader. If it is that loud get it looked at. That way Ford has a record of it. My manuals all of mine made a really loud clunk if I went on and off the gas. I was really young when I had my first and it was fun to get on and off the gas LOL.

The 3.73 and 4.11 will make it very bad. I had a race car with 4.56's and it was sever when you went on and off the gas. The more bushings you change to neoprine or stronger material the worse it will get.

Get it looked at. Then enjoy the car..