Re: how would i kno if...
The key to tranny longevity is to tow in whatever gear the tranny will stay in. Generally, with heavier loads, constant shifting from overdrive to direct, and torque converter lock/unlock is an indication that you need to be in a lower gear. Don't confuse OD/Direct downshift with converter lock/unlock. To determine which is happening, hold speed and then with your left foot, gently "touch" the brake pedal while watching the tach. Remember what that felt link and how much the RPM changed. You should notice 300 - 400 RPM increase. Thats the torque converter unlocking and that alone is not stressful unless it happens on even gentle grades. If rpm changes more than 20% thats the OD/direct downshift. You will generally feel the converter unlock first and if more power is needed, the downshift occurs. If that's happening often, you should be towing in direct. Axle ratio, engine selection and load will ultimately determine how much shifting will occur.
