coil problem

[David D.]

Hello,

I have ignition or charging circuit problems with my 68 C-10 Truck.
In fact, after a few minutes runing the coil become very hot,the engine stop and it's impossible to restart.
What do you think about this problem ?
What about to use a ballast resistor, my truck has no. Is stock truck have one ?
How to place it ?
I change the regulator by an old 64 Chevelle one, it seems to be the same, is it ok ?
Is there different type of external regulator on 68 V8 trucks ?

Thanks for your help.
David