Reply to "how to build a strong ZF"

Your wide-body probably has the late 'Super-ZF' that was used on most late Panteras and probably in the original LeMans racers. The std ZF has been found to be good for at least 700 horses; the Super likely even more with its bigger gears, bearings and shafts. As long as it shifts without grinding and you fill it to spec's with brand-name 80W90 with the LSD-slip agent in it (std nowadays), the thing should outlive both of us with about any horsepower you can stuff in there! One Pantera racer currently runs about 700 bhp thru his with no problems, and a second had his ZF buckled to a 572" Boss-429 that produced over 900 horses. He had a couple of self-induced problems... like getting air over a bump at an estimated 220 mph and not letting off the gas. On landing at full throttle, the input shaft snapped like spaghetti.