TexasMidget it is as you surmised the bearings and syncros are what wear out. This pretty much goes for the 56 series as well. The 3rd gear syncros in the 60 series in my car would work fine for a street car but with the race car it's worn just enough that it's unhappy with my 8200 rpm shift point. It's OK on down shifts but you have to be very deliberate upshifting.