There's a pretty large hex shaped sheet metal flange (or bell?) in the middle of the driveshaft above the heat shield & exhaust pipe. It'll be rusted together a bit, but with some PB Blaster and back-breaking effort you can loosen it with large pliers. I used a big set of channel lock slip-joint pliers (and threw out my shoulder). The two parts of the shaft are splined pretty tightly, but are only secured with an internal rubber compression sleeve. I didn't need to shorten the shaft very much, the diffs are nearly identical other than the medium case being a bit fatter.
Be sure you clean out the hex bolts on the half shafts really well, they're easy to strip out. I found the easiest way to re-mount it was to jack it up and get the driveshaft flange studs threaded first, then the four large upper subframe bolts, then the half shafts, then finally that rear "ear" mount. I also had to bend the rear mount a bit to get it lined up.