1988 F350 Dump Truck Clutch Assembly

I have replace the entire clutch assembly (flywheel, pressure plare, disc, pilot brg, slave and master cylinder with "Ford Parts". I have bleed the system numerous times but the clutch is not functioning. It started out fine, but after sitting, it lost all clutch pressure. Also, the new assembly is much softer than the one I removed. It is an 11" pressure plate with an E8 5 speed manual trans. Is there a rating on these clutches as the is with car clutches (i.e. 2800 lbs etc) I am at a loss now because the pedal doesn't return either.
Thanks,
Bob
VIN - 1FDKF37HXJKA61796
F-350 Heavy Duty Dump Truck - Over 8200 lbs.
E8TA 5 sp trans
351 cu engine