Chevy shake

[bestatthat]

So I have a vibration/shake in the front end of my truck. I have a 2012 GMC Sierra 4.8 L20 flex fuel. I bought it with 20in tires they are in excellent shape amp grippers. So it started with a steering wheel rock it would only happen at 60+mph nothing major couldn’t really notice then couple days go by it starts vibrating at 60+ with steering shake starting at 40mph so I started looking around seen sway bar bushings shot replaced those didn’t see any weights thrown so I’m puzzled. Pick the truck up on stands start moving everything trying to find something loose. Well I noticed that the rack and pinion bushing was slightly loose also found that the rear driver axle was bent replaced that and still vibrating so I started moving tires around still same thing then I tried eliminating tires by putting spare on each corner. Finally I got the spare on the passenger side front vibrating gone smooth at any speed. Picked the truck up again an noticed the smallest bit of play in the inner tie rods on both sides what gets me is that they both have exactly same amount of play checked under the boots they looked nice and greased then I put a crow bar between rack and wiggle for play the passenger side bushing looks to be loose around rack moves a good bit center bushing on rack looks good it nice and solid. I’m just trying to get an all around what should I do to keep this truck in good shape and get rid of vibrating also put crowbar between each A arm bushings with a little force I can make the slightest movement doesn’t s remnant like it would be to much. Sorry about long story just trying to learn a lot about this truck an what to do to make it a 300k mile truck