I have a 2004 Chevy 2500HD 6.0L with 58k miles on it. I only drive it on the weekends but the other day I drove it to work ~16 miles interstate and noticed at the end of the work day a puddle of coolant under the truck. The leak seemed to be coming from the front of the motor but i could not find the specific location of the leak. I cleaned up the coolant off of the chasis and had one more visible leak since then that I still couldn't find. I have had to top it off with coolant 3 times since then. However these last times I didn't see any coolant on the chasis. Any suggestions on where it is coming from / going to?

Thanks for any help.