the 545 is a 4 speed trans. The added 5th gear is in the computer. It uses the 2nd and 4th gear clutches to create a passing gear. It's known as second prime. This gear is weak because your using the small 4th gear clutches in a high tq envoment. (ie cruzing down the free way and hammering the throttle to get around someone going slow) your applying a high load on the weakest clutches. And they are known to fail behind stock hemi's if abused enough. But we are compairing apples and oranges when your talking a 5000 pound truck vs a 2800 pound car w/ the same trans. The loads on it in a car are much less. I hope this answers your question. You can read a bunch about it on dodgetalk.com in the 3rd gem ram section