2000 Montana questions

I have a 2000 Pontiac Montana with 161K on it.
Service history: 20K ago, both front wheel bearings replaced. 10K ago, transmission replaced. Drove though mountains loaded full with air
on and in overdrive. :) oops.
Have terrible wobble in the seat of my pants. Was told tires are bad and they are bad. Had front end alignment done and it was way off. Put new tires on and it drive a heck of a lot better.
I noticed it still wobbles at 45mph to 50mph. If you let up on the gas it is smooth, once you give it gas the shaking begins. I noticed if you turn left around a corner at 30-60 mph it vibrates slightly. It does not do this turning right.
I replaced the cylinders and shoes on the drum brakes in the back. I noticed the struts are crap and the shocks in the back are shot. I know I can replace the rear ones. How hard is it to do the struts? Would I need a spring compressor or would it be better off letting someone charge me a TON to do it for me?
Is it the wheel bearings, the struts or the transmission causing this wobble?
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