bad coolant leak

Hello all,
This is my first post here and I'm glad to have found this board.
I do have a major (i think) problem with my coolant leaking. I have a '97 1500, 350 and it is leaking coolant like crazy. I jacked it up and looked at the top and bottom radiator hoses and they are both just fine.
It looks like the leak is coming from somewhere behind the engine (I hope it is not a cracked block). Is the heating core back there or something else that might be back there leaking? I'd appreciate any help anyone can give me. Thanks

it could be a freeze plug in the back of the block ( located between the transmission and engine).

I bet you it is that lame rubber gasket on the lower intake manifold. I this case get it fixed asap! because you probally hav coolant going inside of engine's vacumm as well as the outside. Get the complete gasket set for both manifold's (upper, lower) and get Ultra Black sealer by Permatex. The felpro sealer is included i kit, but I dont trust it, Felpro is not in the busines of sealers and gasket maker's. but they make 1 hell of a gasket.

thnaks for the input guys. I took the engine apart and guess what I found, yup a bad head gasket. Just what I needed. Oh well, thanks again for your help.