Drawer Slides for Wide Drawers
`There are many slides that will handle #75 to #100 lb of weights.  See one hereThese drawer slide weight over 1-1/4 # each and 2" in height.
  I believe your drawer  will be more an issue at 36 width than the slides. The drawer that comes with the cabinet will not hold very heavy weight. The pre-built bottom would be too light. I built drawer 36" deep and about 30" wide with 1/2 plywood for the bottom. My drawers were filled with dishes and quite heavy. I use heavy duty full extension slides that rated at least for 100#.