No clutch brake in the truck?

I disagree. An original Eaton 1 piece when properly used should outlast any clutch. The fact that the OP is getting ready to install the 3rd clutch brake in there tells me something is amiss and that the clutch's days are likely numbered.

 

Death of clutch brake is trying to stop the truck with it!

 

I had a rocket scientist on our night shift put 3 clutch brakes in the truck in 2hrs and couldn't figure out why they kept getting smoked when the clutch was stepped on.
Clutch was buggered and wouldn't release and the poor clutch brake was trying to stop the engine.

I'm also with @Goodysnap with the one piece clutch brakes being far superior. They have an internal torque limiting slip clutch to try and stop abuse of them.

Also the handcuff style 2 piece ones are crap, the puzzle ones are alot better.

 

I think people see the material thickness of the brake and think that thicker is better, maybe? I have heard some guys say they install a 2 piece with a NEW clutch. Dont understand that. Clearly the person that installed this guys clutch did not have a clue. Either no brake was installed or the 2 piece that was installed failed..........or vaporized..........ha.

Either way if the clutch truly isnt that old a new brake and proper adjustment should bring it back to working order........for now.