new clutch not engaging?

[AussieinNC]

There are two different height throw out bearings...one is taller than the other...

If you used a tall throw out bearing with a tall pressure plate, the tall throw out bearing will bottom against the base of the trans snout and prevent the pressure plate from applying pressure to the clutch plate..

You can check this easily....place the trans in Neutral, apply park brake, then slide under the truck. Remove the clutch release rod from the Z link and the release fork....then try and spin the clutch plate ...use a flat screwdriver and access the clutch plate between the pressure plate and flywheel....if it spins you have found your problem....

I am assuming you have the correct clutch plate for your trans...you did check it was correct before you installed the kit?

What trans is installed?