Several lessons learned by me and others here on this topic. The key points are:
- GM recommends a minimum temperature on the 6L80E of 150°F for normal operation, and with the tru-cool you’ll be lucky to see 130° most days.
- Mounted in front of the radiator, the Tru-cool blocks so much airflow that it creates cooling problems for the radiator engine when towing - even in the spring and fall.
- Plumb the radiator’s water to fluid cooler in line before the aux cooler, regardless of climate. It will warm the fluid when cold and help cool it when hot.
- If not towing, I recommend a smaller cooler than the 40k of mounting it in front of the radiator. If towing, mount a fan forced Derale 13560 or similar below the front bumper.