I've got the same 46RE everybody whines about in the RAM trucks in my Jeep. It's a perfectly good tranny, with a few fixable exceptions.
In stock form, the OD unit clutch apply pressures are a bit low, and the OD unit cooling flow is inadequate. Thus, towing in OD is bad (although these can be fixed with valve body mods, which I've done to mine). In addition, the check valve in the tranny cooler line can fail and clog, causing the tranny to overheat.
If you want one of these to live a long, healthy life, make sure the governor pressure sensor and solenoid are good, make sure the TV cable is set correctly, and put in a shift kit to bump up the shift firmness, clutch apply pressures, and drill out the OD cooling flow hole in the VB a bit. The trannies were set up to shift soft for comfort, but not to last from the factory. Also make sure you add a nice, big cooler, and keep the fluid fresh.
My tranny is at 125k miles now, and shifts like a champ. I tightened up the TV cable a bit when I got it at 100k to firm things up a hair. Once I did the engine mods, I put an upgraded valve body in the tranny (at about 120k). I would now feel comfortable towing in OD on flat ground, and lock it out on the hills (I never used OD with a trailer stock). I also added an 11x11" cooler to it shortly after I got it, and then bypassed the radiator cooler.