A friend of mine had one that lasted 3 hooks, but here's the deal: the final pull that did it in was a gravel track, and he tried 5th low. He did fine, but when he stopped at the end, he took it out of gear and let the pedal back out. When he pushed the pedal back in there was some nasty sounds and bad feeling to it. Had to be trailered home because we thought it was coming apart.
Took it all apart, and the clutch facings had "welded" to the floater and flywheel, then when the pedal was depressed it ripped big chunks out of the friction material. Ugly!
SBC totally took care of him. They said that in an effort to make the clutch more streetable, the plates have a very slight taper ground to them (and of course this line of contact on the outside was where the material had welded). SBC then changed it for sledpulling by grinding the plates dead flat. Further, they warned him that when running a big gear, at the end, depress the pedal and keep it depressed just to let everything cool off a bit. Feather it into reverse, then feather it forward and then let the pedal out.
He's had a bunch of hooks since then with zero issues and it feels great.
Hope this helps.