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I have a rattle in my 2006 s281-sc. I have it a 60-70 mph and 5th gear It sounds like its coming from the passenger floor board and its metallic like a heatshield. all bolts are in the tranny plate and all heatshields are tight has anyone else had these issues and if so how did you fix it?[/align]

 

I have a rattle in my '05 GT that sounds like it is coming from somewhere behind the dash around the centeror maybe closer to the passenger side. Dunno if it is the same as what you have, but it sounds like someone dropped a ratchet behind the dash and it is vibrating on a steel plate. VERY annoying. Happens when my car gets between 40-50 MPH. I took the freaking dash apart and checked everything I could get to and nothing is loose. If you figure it out, please let me know what you came up with...may be the same problem.

 

https://mustangforums.com/m_3772748/mpage_1/key_/tm.htm

Could it be this? If I can't get this fixed on mine soon, I'll be taking it to the dealer to get that plate modified or removed.

 

Mine is distinctly behind the dash though...sounds like something rattling on the Shaker unit or something. Maybe something behind the glove box. This is interesting info on that link though...I'll have to keep that printout for reference in case this happens to me!