Engine/Transmission (1998.5 - 2002) Check your trans. cooler lines!

I got an e-mail talking about poor performance with my fathers truck while cold in the morning.



Today I get an e-mail saying that he is stuck in the middle of the road behind his driveway. with the trans. slipping (this is a brand new trans. /about 3 mos. old). Truck is a 2000 2500 QCLB 4x2 auto.



After checking the fluid, it was low. He added a few quarts and all was fine. Later in the day, backing out of a different parking lot... Same problem.



Turns out that one of the trans. oil cooler lines had a pin hole in it. He lives beachside not too far from my place but the rest of the truck is like new underneath. Weird?!! The salt does not really affect vehicles down here unless they are actually driven on the beach and through the salt water.



I always harped on him about gauges, but he never listens to reason.



What is the possibility of the transmission being damaged?



He says that the line has been replaced and the fluid is back up.