I can't tell you how because I don't have a manual for a C60 but I can offer you an idea I think is worth considering.
Pull the drums off an check the brakes out,just to make sure that the system is capable of giving you the brake performance your looking to achieve and stop that big thing.
I say this because of the surprise I got when I pulled the drums on my 2ton.
Now of course if you already know the condition of everything inside of the drums it won't be an issue, but you didn't say if you already had done that.
