One of the weakest links in a performance diesel truck is the transmission. If you've added some power to that Power Stroke you may want to look into a Dominator Transmission System from Level 10 Products. Its fuel efficient design is built to withstand up to 1000 hp and a towing capacity of 20,000 lbs.
Contact Level 10 Products at www.levelten.com or call them at 973-827-1000.