I just posted the other day about my 4bt with a broken camshaft. A bolt had came loose out of the gear case & broken 1 tooth off the crank gear. The kdp is still in place. Looking more closely I noticed the engine had not jumped time from the missing tooth. The only damage to the gears are the crank gear & 2 small gears on right side of engine, no marks on cam gear. This leads me to believe that the engine has probably ran a while with the missing tooth. I talked to the service managers & some mechanics that work on 4bt's & they said broken cams are the most common failure. If 6bt's are the same engine with 2 more cyls.,it would lead me to believe that they would experience even more cam failures since the cam is longer. I haven't heard of 6bt's having this problem. Could the problem be that the 4bt does not have a harmonic balancer? If I put a 6b harmonic balancer on, fix the kdp, & loctite the gear case bolts will broken cams be a thing of the past?