After running TST with stock tranny and converter I was having trouble. Seemed with it on 4/4 something slipped with cruise set around 68MPH towing my trailer. I then got brave and set on 6/6 empty and something different slipped at 48MPH. After that I had to leave box on 1/1 to not have problems empty. 12,000 miles on truck. Tore tranny down found slight wear on high gear clutches and wear on the bearing spacer in overdrive unit. All of this is normal for a high mileage truck but not 12,000 miles. Sent the converter to Layne Ford at PTC, they do all my racecar stuff. They said the converter had no bad wear until I mentioned the mileage LOL. They recpommended the suncoast valve body so that's what I got. Boy you really pay for the minor tricks they do. PTC charged $950 to tripple disc the converter and make it an extra low stall a great deal as they always do great by me. Well my buddy doing the tranny had never riden in this truck prior to the work. He called me and asked what the box was on and I told him what to look at. It was on 1/1 due to prior difficulties. He said, " There is more?". When I got there I immediately put the TST on 4/4 and we went for a stroll. The pavement was wet and the grab handles on the passenger side need replacing now. Boy what a difference.