Thoughts to share
>) I agree that the sound is due to the resonant frequency from the belt which relates to how tight it is and the open length between pulleys. Think of this as the same thing that occurs with a guitar string. With that in mind, I looked to see if I could obtain a Goodyear gatorback belt as I had used on another vehicle and from my personal experience, it was the quietest belt I have ever used, in fact I thought something was wrong it was so quiet.
During my search I found that Goodyear and Continental belts are now the same company and made at the same location along with the knowledge that Goodyear belt name is going away. In addition, I looked up the correct belt on RockAuto and under the "info" tab I read that the "special" design of the gatorback belts "helical" is being phased out now and if you order, you may receive the "helical" design or the oem standard design. In any case, I wanted the original design as that design was specifically made for quietness and long durability. The only place I could find that still sells them (I am sure there are other places as well though) is through Ebay.
I also determined that for Continental belts (as well as similar for other mfgs), that the belt length is in the part number. So the part number that mini4mw listed being the Continental Part #4060998 means that the belt length is 99.8" long. If you reference the original belt mini4mw referenced it is the Ford/Motorcraft Part #: JK61004B (8620) which my research tells me that belt is 100.4" long. In any case, I suspect with such a long belt that an inch +or- doesn't matter, my research though listed for my 2010 V10 to use the Continental (or Goodyear) belt #4061000 which is 100.0" long.
In any case, you can still find the quiet design and I am not sure if I can share an ebay link, but check this out and look at the pictures of the belt to get a better idea of what I am talking about along with a chart showing this belt to be much quieter than the competitors (which I take as a grain of salt seeing how they don't show the name of the competing belts mfg). This is the belt I purchased last night, however from a slightly less cost seller, I shared this one though as the pictures are informative.
Also, I found that this is the same size belt for almost all E450 V10's starting from at least 09 to 2019, likely as early as 2003 up to 2020 (assuming the same V10 engine) but I didn't confirm that so do you due diligence, but I suspect it is the same. Check out this link, I am not trying to sell you on this, but will tell you that getting this same belt in the future may be challenging as they phase these out, likely to make more money with the standard belts. Notice how this belt has diagonal cross cuts which is why it is quieter (imo) as the helical cuts change the resonance of the belt.
https://www.ebay.com/itm/4061000-Go...465210&hash=item3fee3aa097:g:ZrgAAOSwLq1ftFzt
