So after roughly 500 dollars spent on random parts, six different axle shafts, i finally figured it out. The shaking was caused by a shitty AutoZone brake drum that was casted out of round.
Put it on stands. Pull the wheels and brake drums and turn the axles and watch the axle flange for runout, or check it with a dial indicator.
Glad you found it. Sucks that an inferior part caused you that heartache and cost you that money.
my 81 malibu felt like crap at about 55 and up. my mechanic friend said most of those problems were in the driveline. i found a driveshaft for 40 bucks and the problem went away. my original driveshaft looked good and the u-joints were good also. something was wrong, but i hope you find your problem.I drive a 1986 MC sport coupe, 4.3, th350. When I drive at low speeds, it feels like I'm driving over small bumps, but when I go past 45, it shakes so bad that I don't want to drive it anymore. I have put the car up on jack stands and put it in gear, and when the rear wheels turn, they seem to roll out of round. Driveshaft spins straight, u joints are all good. I have replaced upper ball joints, all motor and trans mounts, harmonic balancer, and it does this with any set of wheels on it. Please help, I'm at my wits end here.
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