I've got a '95 F-150 351 and my father in law and I just yarded out the engine to rebuild it. We've bolted up the bell housing and as we attempt to attach the flywheel to the torque converter the nuts strip themselves as we tighten them in. Both manuals we have (Chilton's and Haynes) say to torque down to 75-90 ft-lbs. Is this too much? Also, it is possible these are one use only nuts? Do they need to be replaced since we've taken them off? We've had to cut off 2 nuts so far. Any help/advice greatly appreciated, thanks!