Jason, heres my 2 cents worth of advise. The floor pan welds to lip of the rocker in one place, you could slide it front to back or side to side, but vertically there is one choice, it welds to the lip the old floor pan was welded to. like mentioned above, bracing the body to hold it alignment is really important, it will move around more than you think. I would only do this with the doors in place. My advise is hang the doors. check the doors fit at bottom of door to rocker panel and rear edge of door to front edge of quarter panel. jack the body around accordingly to get good alignment and brace it. this will verify that it is square and that the doors will fit when you are done. I looks like the new channel rises up too high in the middle, the transmission tunnel area. It wouldn't be the first reproduction part that was made wrong, or the first time one had to be cut apart and reconfigured. but definitely something could have moved and you need to make sure you have it squared up. In the end the channel has to fit tight to the floor pan and get welded to it all the way across the truck including the tunnel area.
