yours may be a bit different but i was on here asking the same thing but i found my dad found the problem very quickly...
i asked on here what the part might be called but no1 knew...
http://img.photobucket.com/albums/v6...IMG_1945-1.jpg

we took that crap off and this is what we found..

http://img.photobucket.com/albums/v6...y/IMG_1949.jpg
http://img.photobucket.com/albums/v6...y/IMG_1953.jpg
http://img.photobucket.com/albums/v6...y/IMG_1954.jpg

the one piece was cracked so when we took it off it snapped in our hands... and the other rubber holder was worn to nothing... when i hit it past 2000rpm the car would shake, more so when with higher rpms and now... handles like new, no low rpm rattle, feels liek there is no more gear changes... check that out, hope u fix whatevers causing this.

.... and as for my album name being _ohbaby, uhm thats my girlfriends photobucket, just to clear that up

 

yo headshock, check your tirerods... a slightly bent tie rod could cause vibration...

my car got a bent tie rod in mexico but it was still driveable and that causes vibration starting around 43mph and its at its worse around 70mph....

i know you said the alignment is ok, but have you put it on an alignment rack somewhere and actually had someone check for bent parts??? If not, I would start there. Good luck man, it sucks when the car is vibrating, when people get in it they think its a POS, lol, ive been there and done that.

Let us know what you figure out cuz so far were all stumped.

 

Djuro, that first picture of yours looks different than my car... do you have an Automatic?

I don't know about this being an exhaust thing... if it were contacting the car somewhere, I'd no doubt hear it, right?

Also, this is vibration is not an RPM related thing... If I throw the car in neutral and coast at 73~ mph, it'll still be doing it at idle.

The rain is what has me stumped... I was really thinking it was the driveshaft, but now, who freaking knows. :P I'm going to try and get it looked at today.

And as for the tie rods/bent parts/alignment... I'm quite positive. My tie rods are a few months old, they were actually the first thing I changed when I set out to get rid of the vibration... it had an alignment then, too. Control arms were all replaced last week.

The hub assembly is original equipment with around 80k miles on it.

 

i have an 02 manual 1.8TQ... thats why i said yours may be a bit different but my dads 99.5 had a similar problem a few years back... i was younger than and dont really remember how it looked thats why i said it may be a bit different, i asked my dad the name but he doesnt know the name in english...

 

I had a similar issue with a previous 4 wheel drive car. It was the rear diff was shot and the ECU needed to be flashed.

 

Oooh I hope it's that! [:@]

 

I had the car at my mechanics today for like an hour on the hoist... driveshaft seems fine, exhaust isn't hitting anything... everything seems good. He told me to check my brake rotors... he said sometimes they can cause this -- just like a wheel can be out of balance, so can a brake rotor. He said this is often due to cheap rotors... and I've got Zimmerman cross-drilled... so we'll see. I might just go to OEM plain faced A8 rotors and see if it helps. Jeebus.

On another unpleasant note, I think my power steering rack may have issues. Fun.