[mr48chev]

You did put the disk in with the raised portion for the springs to the back? There have been cases where guys have put the disk in backwards and it won't release because it is catching on the heads of the flywheel bolts.

I agree with wrechbender as I usually do in that you don't even want to "preload" the clutch as that will eat up release bearing and disk.

If you have the cast bellhousing with the cover on the bottom I would first do as he suggested and get under the truck and watch while a helper pushed the pedal. The pressure plate should release and you should be able to reach up with a screw driver and turn the disk with the trans in neutral. I it doesn't turn with the pressure plate released you might slip it back a bit with the screw driver and see if it will turn then.

If the disk is still hanging up when you can see that there is space between it and the pressure plate you could take the bolts out of the pressure plate (maybe sticking a couple of longer bolts in place to slide it back on so you could look up inside and make sure it is oriented right before taking the whole thing apart.

I've replaced at one clutch disk that someone else replaced that had the hub bent because the guy who installed it let the weight of the trans hang on the splines of the disk/input shaft while installing it. That one wouldn't release all the way.