Like, the title says... Doesn't matter if it's in drive, reverse, park, it still vibrates. I can feel it in the floor, the steering wheel & generally throughout the vehicle.

The vehicle vibrated from day one (used w/ 106k miles at the time), but the vibrations have lessened as I've replaced parts of the suspension.

Here's a short list of all replacement parts:
1. Wheels & tires
2. Rotors & break pads
3. Front shocks (rears too, if King will ever finish making them) & bump stops
4. Front & rear sway bars.
5. Differential crossmember (upgrading bushing)
6. Steering stabilizer

The crossmember intially fixed most of the vibration, but it's come back a bit. I've check the torque on the nuts & they are fine.

Since I'm getting this vibration in park, I can't see it being any part of the suspension. Could this me a motor mount issue?

 

None of the parts you replaced would solve a vibration, while parked...

I doubt it would be a motor mount, as there should be no movement of the motor, if its just idling, unless your punching the gas..

I would lean towards someone screwed up in motor or trans...

 

I had someone shift the vehicle from P > D > N > R & there's no motor movement, so yeah, I doubt it's the mounts.

I came across this list (first answer, 8 options): engine - Car shakes when in gear at red light - Motor Vehicle Maintenance & Repair Stack Exchange

I have no check engine warning, so it's nothing obvious.
Considering it has over 100k miles on it, would spark plugs be the go to problem to start with, then go down the list or is there something else that I should specifically look for first?

 

It could be plugs, misfiring, or maybe a bad sparkplug wire

 

Considering there's 112k miles, I should replace them anyways.