Not sure what you mean by "heavy duty transmission cooler." Traverses with the tow package have a "heavy duty radiator" that incorporates a transmission cooler. So if you have that, you have the factory tow package, which is advertised as good for 5200 lbs. If you don't have it, then you're only advertised (and warranted) to 2000 lbs.
If you want to haul 3300 lbs, I would strongly suggest an aux oil cooler. You can get them from etrailer.com.
If you want to add more of the tow package, PM me your email address and I can send you a lot of info on parts and installation. (Still won't be warranted for more than 2000 lbs, though.)