"Built" 4L60 lived fine for me behind 496 / 600HP. No doubt, however, that it was maxed!
New TCI X6 (6-speed mod'd GM 4L80, rated 850 ft/lbs in "base" configuration) is in there now. Awesome almost beyond words.
GVG works, but cantilevered mounting and strange U-joint angles take it off my short list. Never been in a car with one that didn't have some vibration at some speed or other.
