RTV-X1100C - VHT extreme shake

Hey fellas. I have a Kubota RTV-X1100c that I recently purchased used. Runs and operates great but has developed a pretty extreme shake when accelerating in any drive gear. I have narrowed down the problem to be transmission or hydraulic related. I am hoping that maybe I've missed something, and someone could shed me some light, before resorting to unnecessarily replacing parts..

Here's what I know:
The engine revs great (in neutral).
The machine does not shake as excessively when lifted...

RTV-X1100C - VHT extreme shake

RTV-X1100C - VHT extreme shake