Thank you, ship and smj.
I will never tow over 3500 pounds again. However - driving for 6 hours through the rockies - changing 1km of elevation in 10 minutes and a few times throught the drive - i would imagine this could push things too far...
Maybe my transmission is not as good now as it was... So I'd like to be certain it will not happen again - at 3500lb total.
The only way may be shelling out a few hundred for the bully device someone mentioned...