I'm having some vibration between 70-75MPH with my 300SDL. Also seem to be having some front tire wear. I had the car aligned and put new tires on the front. Rear tires look good. Vibration improved with the new tires, but its still there.

It doesn't happen all of the time. It seems to actually be worse on smooth concrete interstate than asphalt 2-lane highway. At around 60MPH the steering wheel has a slight back and forth oscillation. I'm thinking bent or worn suspension parts. As far as I know, the suspension and shocks are original. Can poor shocks be causing this? Where should I start?

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'87 300SDL
'96 F250 Crewcab PowerStroke
'00 Kubota L2600
'66 Malibu ragtop (SOLD, sob)
'01 BMW M3 ragtop