The problem with the lock up converters was not the fact it was lock up. The problem is they try to make all the shifts real smooth so customers don't notice the shifts, %99 of customers want a silky smooth shift. To get a smooth shift you engage clutches and bands more slowly, this allows them to heat up and burn then fall apart. The old fluids that chrysler used allowed the clutches to grab each other faster and burn less but shift harder. The ATF+5 is very low friction for smooth shifts and is bad in the trannys that were originally desighned for the higher friction fluid, the low friction fluid was a cheesy way to soften the shift. I worked at a dodge dealer in 01 and 02 and we replaced TONS of trannys. It was NOT an issue of service or not as 1/2 of them were not even due for their first service. They had new TSBs almost every year for all sorts of little things in those trannys, I like most people figured I was just seeing the worst in a manufacturer because I was a dealer tech, then I went to Toyota and replaced 2 a year instead of 2 a week. The newer mopar trannys are much better at dealing with the crappy new fluids unlike the a-500 and 518s that were desighned to work with the old high friction fluid. I always use Type-F when I build a tourqueflite based trans and have not had a single comeback on one (knock on wood).