I've also got the flywheel bolt problem.It's an fg xr6t ute 6speed & It's running a mal wood option 3plus kit.One of the bolts snapped & ruined the clutch ,flywheel & crank.So I've replaced them with a new clutch, flywheel & I also put a new f6 engine with 20 000ks on it in.This time the bolts where tig welded around the head of the bolts which was recommended by several reputable builder's. Well now I'm in the process of putting a built engine in so the old one came out the other day.When we pulled the box out we noticed that the clutch plate had grooves & marking on it like it's flopping around.Would this be where the vibration & imbalance causing the flywheel bolts to loosen be from?or would that stem from something else?Any help on the subject would be awesome thanks.