Radiator Hoses and Thermostats and ?

It's time to change/flush the coolant, hoses, and thermos. I've searched as best as I can, but can't find too much specifically about part numbers and such. Where is a good place to buy the parts I need? NAPA? dealer? What parts do I need? I know I need upper, lower rad hoses, and tsat's. But are there seals or gaskets that should be replaced as well? If you have part numbers that would be great. I think I understand the flushing / bleeding procedure. It's in the owners manual, isn't it? It's a 2001 Duramax.
Thanks Guys,
Jim

I'd stick with GM parts. The lower hose assembly costs about $130. All spring and screw clamps are included with a new hose.

Use Dex-Cool mixed 50/50 with distilled or de-ionized water. Somewhere here in this 6600 forum is a thread/post with a pic I posted showing the coolant drain plug locations on the block.

Jim