Jschlegs28

This is my first post to the forums, so take it easy on me..!
I have a 1992 SC300 which i purchased in November. To the date I have replaced Brakes, Tires, alignment, valve cover gaskets, spark plugs, and spark plug wires. My next project/ problem occurred when driving down to LA. After driving 100 miles, i was stopped and idling at a stop light when my baby overheated so i immediately cut the engine and pulled over. The coolant overflow tank was completely full to the top. After letting the engine cool down, i started it up again and the coolant went back into the radiator and drove fine to my destination. No coolant was lost, NO milky oil on oil cap/dipstick. NO white or black smoke from engine. I figured it was a sticky thermostat and I would replace it when i dove back to SB, carefully keeping an eye on it.
After driving back to SB, about 100 miles in, My SC overheated again. This time i found a boiling of the coolant in the coolant overflow tank (which was completely full to brim again), and coolant on the under shield of the car (which i assume is cracked radiator, and i will check it when i get home in a couple hours), Also the Upper radiator hose was burning hot while the lower hose was ice cold (including creating ice on itself).
Thermostat is an easy job, and Radiator doesn't seem too tough to change either...
Suggestions on what parts i should use/ any advice when taking up this job?
Any thoughts and opinions would help greatly!

P.S. Ive read other forums and step by steps, but none are for a 1992 SC300 auto.

Thanks for your time, I just want to get my baby back on the road!

Jschlegs28

After looking under the hood, adding more coolant, and letting the car warm up, i noticed the leak was coming from the water pump. Tomorrow I will replace the Waterpump. Thermostat, and radiator cap.
Is there any step by steps for the water pump?
More Specifically: Ive been hearing missed signals on the difficulty of getting the harmonic balancer off...
I do not have a breaker bar, but i do have the 1/2" socket, 19 mm, and 17 mm.
Any advice is greatly appreciated!