[mrein3]

Two points.
1. I had an auxiliary cooler line blow off. It does not take long to pump a transmission dry. I used the rubber hose supplied by the manufacturer of the auxiliary cooler. That is what failed. I then bent hard lines to reach out to the auxiliary cooler then double clamped very short pieces of rubber hose. That was about 15 years ago. Maybe 20.

2. Regarding how to plumb in an auxiliary transmission cooler. In a cold climate like where I live you want to run the hot fluid to the auxiliary cooler then to the radiator then back to the transmission. In the winter you can have transmission fluid that is too cold. The radiator helps warm it up on a cold day. In warmer climates run it to the radiator then the auxiliary cooler.