Odd low speed vibration
 

OK, I'm no idiot, but I cannot figure out where this vibration is coming from.
at speed it's nearly imperceptible. but from not much above idle, to about 35mph, it increases in feel. I'm beginning to suspect an engine misfire... but the motor sounds so smooth, and pulls soo strongly.
it feels like a shudder in the driveline, but it does not increase much with speed... almost like an imbalanced flywheel would feel... I have gone over the suspension. there is a bad tie rod end near the drivers wheel, the lower ball joints are in need of repair, but not bad yet, the cv joints are heavily cracked, and the driver's side is leaking (makes a neat spray pattern of oil on the floorboard... the flex joint in the rear is showing some cord, and cracking slightly, so that is #1 on my list to fix asap before it comes apart!
the tie rod is #2, followed by the ball joints.
the vibration is not felt in the wheel, but when braking I can feel it in the pedal. and during driving, I feel it in the seat of my pants...
any patterns to follow to trace this?
I suppose it could be the tires, but I don't know. I'm gonna swap rear to front and see if it moves. I know I need an alignment, so that's on the list too.

Quit eating beans and turn the subwoofer down?

I second the tires spec if you know you need an alignment.

May be that flex disc. You can only feel something in brake pedal or seat, that tells me the rear end is where you need to focus.

Great.
lemme know if you have any suggestions to help me isolate the source.

A close visual inspect of other items, the center bearing in particular. Jack the car up and try to rotate the drive (propeller) shaft, feel for looseness.

I'll throw it back up on the lift today and check that out.

Best to pull the driveshaft and check the 'stiffness' of the joint. They usually get very stiff with age as the grease dries up. Unfortunately, there's no grease fitting and the joint is staked in the yoke. There's a driveshaft shop near here that I want to stop by someday and see what they will charge to repair one.

well, I didn't get time to put it on the lift today, brother's work truck broke down, and had to go change fuel filter/pump/oil/filter.... fun. I smell like gasoline!!!! ugh!
I'll get it on there tomorrow...
wish me luck!

I had a similar vibration in my 82 240D project car last week. I had looked at the drive train and didn't see anything, upon crawling under again I discovered a rip in the center bearing support rubber. All fixed now. It wasn't easy to see. Have another look at the upper part of that rubber bearing support.

Check the rear trans mount. I once had a small rock jam in it. It made the car shake like you describe. Until I found it I thought the drive shaft was about to fall off.

LUCK!

Get someone to drive beside and behind you...
and look at your wheels and tires...
and do it at the worst speed....
Then go to the other tests...if needed...

I've been thinking of that same thing... if only I had someone not busy I could do this with...

tires...