unknown vibration
 

I have a 76 el camino. I've replaced ALL the steering componets. Have brand new rear tires and very good front tires. I've got a fresh alignment. ?Car rode brand new for a couple of weeks. It just started shuddering (vibrating) when it is under a light load. Leaving the light it does not shudder. However, after accelerating halfway to the shift point (th 350) car begins to shudder. I baby this car and don't launch hard. I'm 69 years old and don't do stupid stuff. I go from point a to point b. Does anyone have any idea what may be causing the vibration? Thanks in advance for your input.

Drive line? U joints?? Re balance front tires???

How many miles on it and what service have you had done on the transmission?

Sounds like you threw a wheel weight.

imo, vibration only under light load rules out the out of balance wheels...just make sure the lug nuts are tight. Sounds driveline related to me. trans, driveshaft, diff.