Years ago, I rebuilt a 727 for a friend to install in a '73 'Cuda he intended to race. I made sure it had the good stuff in it (4.2 lever, 4 pinion planeteries,, 5 clutch discs in front drum, shift kit). what I did not realize, was that he had no kickdown linkage, and wired the lever back when he installed the transmission. He raced it for a couple of seasons. The next Spring, he called to say that it would not back out of his enclosed car trailer that he used for winter storage. He said it drove in OK the previous Fall. I told him he would have to pull the trans, and drop it off to me. This is when I discovered he had the lever wired back. I pulled the oil pan and discovered that the rear servo had pretty well exploded. The sheet metal spring retainer was distorted, and had been forced through the retainer snap ring, and was hanging on the band apply lever, along with the spring. The band apply strut had been folded over and broke, with the pieces laying in the pan, along with shrapnel from the servo piston. Fortunately, the servo bore was not damaged, so the 727 was still repairable with replacement parts. Tying the kickdown lever back replicates what happens inside a transmission if the gas pedal is at the floor with all linkage installed, with all hydraulic circuits in the trans experiencing full pressure. In reverse, this can be 300 pounds. After seeing the damage, my friend acquired the proper linkage for his car.