My front end shakes at speed 70-77 mph. The steering wheel feels fine, no vibration there, but the right foot holds the gas pedal can feel the front end vibrate. Also feel it more when I let go the gas pedal at any speed above 55 mph.

I just wonder if this was caused from the linkage? My speedometer is 78K miles. Is this time to replace it yet? If so, What are the parts number for these? Thanks of everyone inputs.