[vs800]

I just had the same issue on my 2000 impala. It was a crack in the tank drivers side near the top of the radiator. I could not see it until the radiator was out.

The dog bones and the mount they attach to above the rad need to come out so you can get the rad and fans out. Also remove the airbox and carefully set the ECM out of the way didturbing the wires as little as possible. They are brittle after many years of underhood temperatures.
It is not a real hard job. I bought a rad on ebay for under $70 deleivered to my door. I did alot of price comparing and have found that every time ebay beats everyone. It is chinese but is working well and thats what most of the part stores are going to sell you anyway.If you have any problems post. I don't know about the epoxy, it is hard to get it to stick to the plastic tank.