Severe stability problem

[Alphacowboy]

Guys, after my rear axle swap (put 3rd gen axles front and back out of a 03), I am having some issues that I cant figure out. The front axle has been under my truck for months, and hasnt given me any issues. The rear has only been under the truck for 4k miles (3k of it pulling a trailer from MN to SC and back) I had the mentioned issues with the trailer, but MUCH less prominent) Here is a list of what I am dealing with.

1.) Rear tires are slighty wearing funny, but nothing to bad. Still even wear, just a little feathered if you know what I mean. Fronts are perfectly worn.

2.) Truck feels unstable. It almost feels like the rear is "floating" when going down the freeway. Put the plow on, and it makes it almost scary. To the point it seriously feels like the rear is off the ground!

3.) When I hit wavey pavement, the truck teeter-totters front to back almost to the point of making you sick. The shocks are brand new, not even 4k miles on them.

What I dont get is that the u-bolts are all tight (i'll check them again tomorrow, but I re-torqued them the day after I installed them, and they are torqued to 160ftlbs) The perches we welded on are the ones whe cut off the D80. They are welded right to the side of the AAM factory ones and to the tube. They are flat with the OEM ones, and are very very close to the same front to rear. (one is just slightly forward, but not more than 1/8" and even if that was slightly off, I would think the most I would be dealing with would be a slight dog track.) Brakes are fine, not dragging. Wheels seems to spin freely and wheels are tight and dont seem to be loose. I did however notice that when standing behind the truck, the rear wheels look almost like they are tipping out at the tops. I measured between the bottom of the rims, and the tops, the bottom is 3/8" closer together than the tops. But, i couldnt really get the tape straight at the top (shocks/cables in the way). i hope this axle isnt bent. Been meaning to try and pull the axle shafts to see if they come out, I know if they dont come out, its bent, but its been cold and snowy here the past couple days, and I dont fit in the garage.

Guys, I need your help, I am completely lost here!