first off you didn't give us any information on your truck or trailers numbers to give you a recommendation. 
  We need the truck and trailer year model.
  the trucks and trailers GVWR.
  The trucks RAWR
  is the truck a manual transmission or auto
  You will not get a same consensus on this forum where it come down to a 3/4 ton truck towing a 5th wheel trailer......everyone has a opinion on weights so read between the lines.
 I can tell you now as long as your 2500 Mega Cab is OEM .......it can tow a 5th wheel trailer.
 Give us some help....thanks
 Jim