Vibration 60mph+ when off the gas

[anesthetize]

Hey guys, new Mach 1 owner here. 5 speed 56k miles.

My car just developed a vibration, feels like driveline/rear end related. It starts around 60 mph and up, but only when I'm either barely on the gas or completely off. If I'm on the gas accelerating it goes away completely.

I have searched google a bit and can't find anyone else describing my issue specifically, however my assumption is that it is driveshaft or u-joint related, and if that's the case I will probably use it as an excuse to upgrade to an aluminum driveshaft.

Before doing that, I thought I would ask on the forums and see if anyone can confirm my suspicion or point me in another direction.

Thanks for any help you can provide

 

[Wharf Rat]

Check all of the upper and lower control arm bushings.

 

[Roots-type]

What's done to the car?

 

[anesthetize]

lowering springs exhaust intake, stock otherwise

 

[Roots-type]

I'd look for simple things first. Have you checked that the wheels/tires are properly balanced and torqued? I had a loose wheel on my honda and it would only vibrate when I let off the gas.

After that I'd start to look towards control arm bushings and pinion angle settings.

 

[4a7191a]

Aluminum driveshaft time maybe.
I had that problem years ago