Look if you want to believe what a Ford engineer tells you go right ahead. You can live your life from internet experiences all you want. I prefer to use real experience. You show your ignorance when you say foolish stuff like "You haven't done any of that. Your 1 piece is not part of that system. You just went to the store, bought something, and bolted it in. And now are going crazy because engineer's countered your false story about the 2 piece being faulty." First it just shows you know nothing about how these drive shafts are manufactured, measured or tested. Since you love to believe everything you read off the net educate yourself by visiting a couple of these drive shafts companies websites and actually do some research not just regurgitate things you read that support your opinion. it is called being objective. Second I said my drive shaft went bad at the bearing in 08' after 38K miles of easy driving. When the dealer wanted to replace it for $1200 I looked into it and found out about the one piece units. Now not all are created equal but there are some VERY high quality units out there that have taken what Ford originally did and improved upon it with lighter weight, better materials and smoother operation. Which in turn resulted in quicker acceleration and reduced weight. Since 2008 I have not had one single issue with my drive shaft. So let us count 2008 to 2013 is 5 years and 62K trouble free miles. That means it has lasted LONGER and served my purposes BETTER then the OE unit did. Now the clunk you refuse to acknowledge and keep saying it isn't the 2 piece shaft causing is in MANY of these cars. Most if not all report reduced or ELIMINATED clunking noise when they go from the OE unit to one of the high quality 1 piece units. So how does this happen if the 2 piece DOESN'T PLAY SOME ROLE IN THIS AND IF THE ONLY CHANGE THE OWNERS MAKE IS THE DRIVE SHAFT? We all can't be telling the same lie. Not to mention you still haven't answered my question as to have you ever actually compared the two and tried one for yourself or are just repeating what someone else said? You are like that state farm commercial where that young lady believes everything she has seen on the internet. Enjoy your french model sir.

 

05gtowner I have to agree with you and the ford tech. Only you know your car batter than anybody if you heard a clunk or excessive backlash well its what you heard. Is a solid one piece better that the stock two piece? Hell yeah for performance of course if your modding your car safety is not a huge concern but for an engineer they have to pass emissions and safety test so of course its going to hurt performance. But if I were you I would still get that backlash adjusted, and hell while your back there throw in some 3.73s.

 

Yeah I agree it def. could be excessive backlash or a combination of loose tolerances in the trans and diff but the oe shaft exacerbated it due to its weight. I mean almost 40 pounds of rotating mass is going to bang things around in there especially if it already loose. But to say that the shaft doesn't play a part in the clunk or noises we hear in these cars is foolish.

 

I'm thinking of getting the Dynotech as well. I have a Coast 4" but I had a clearance problem once and the driveshaft touched the tunnel. The shaft was marked up a little and I've been nervous taking it up to really high speed. It starts to vibrate at about 110mph and I don't want to be scared of it failing on track days.

 

The dynotech shaft is AWSOME as I said before, no adapter flange a true one piece shaft.
3 inches as well. This one has absolutely no vibrations at all, 16pds.

Another surprise is I sold the old one on eBay, and when I took it to the post office for shipping it weighed in at 42 pds naked. Heavier than I thought.