I have looked over my FSM'* and so far found nothing, I know where it should be if I have one, but my problem is the stupid plastic underbody cover, I removed all of the bolts, and the pop up/door cover style clips, I managed to get the rear part of it to slide out from the bumper cover I believe it is, but the front part will not pull out so I can get to the lower radiator hose, or petcock.
I have never had so much trouble removing one of these, it almost looks like the whole bumper has to come off, is that is the case I'll just take it to a shop to flush it, as it is not worth all that BS.

Here is info from my FSM, sure looks like the front fascia has to come off, so I guess I'll have to remove the headlight assemblies, and the fog light assemblies to get it off, not hard, but ridiculous, wtf was GM thinking?

Here is a link to the pics from the FSM, I had to use my phone to take them, as the FSM was too big for my scanner, lol

Remove Radiator Air Baffle and Deflector - Album on Imgur

What does not make sense is the fascia is connected to what goes around the front wheel wells, and removing screws from that is not shown there, so I am not sure why the whole thing looks like it needs to be removed to get that plastic cover off that is blocking the petcock.

I tried removing the screws from the lower wheel wells, and the clips under the hood area, but that fascia would not budge, I guess the lights have to come out as well.

I read up on it a bit, and I am thinking that there may be no petcock, even though the FSM says there is, because why the hell would they make it so hard to get to?
I have to find a way to drain the coolant, and flush it a few times, but without getting that plastic piece off, I cannot even get to the lower coolant hose well, if I did it would drain out all over that plastic baffle crap..

Really close to putting it back the way it was, and just taking it to a shop to drain/flush, the thing is I'll have no choice but to do this after the LIM job.
Hell come to think of it, I am not sure how to get the coolant out to do that, that plastic baffle has to come out.
Hopefully somebody has a clue as to what I need to do to remove it, I have tried almost everything. I spent like 2 hrs trying to remove it, I am half temped to put a cut off wheel on my dremel, and cut the damn thing off, of course then water can easily splash up into that area..

Got it, you just pull the plastic down a little, and then you can reach the petcock, it drains out of an area that does not even look like it would be a drain..
Turns out you do not have to remove that plastic at all.

Well, I got the new coolant res installed, coolant is draining, but very slowly, which worries me a little, it drained way faster on my Park Ave, so I am guessing something may be a little clogged, just not sure what.
I have not removed the thermostat yet, but I'll probably remove it tomorrow, and put the hose back without it.
That way I can flush it a lot easier, or I may just hook my scan tool to the car, watch for the coolant temp to reach about 200F, then give it a few minutes to run after that point, then let it cool enough to drain it.
I seen in my FSM is says do not use chemical flushes, but I already bought some Zerex ZXC01 Super Radiator Flush, and as cruddy as the rad cap was I am thinking maybe I should run it, just maybe not leave it in there too long.
It says safe for aluminum, but it is the seals I am more concerned with, so I'll take any tips or advice if anybody has any.

If I remove the thermostat, can't I still turn the heat on and let the water travel through the heater core?

Did you pull the petcock completely out? Did you open end the system elsewhere?

I did not pull it out completely, but unscrewed it most of the way, I also removed the rad cap.

They come out......and then things really start to flow.....did your'* have a tab to turn, or was it one of those you stick a 1/4" extension in to turn? Either way, they both will come out.....on the 1/4" you have to pull as you turn it.....

I figured it would come out, but being that the plastic shield/baffle thingy was still partially in my way, I decided to not take it out, as I was afraid it would be tough to get back in.
Mine had 2 tabs to use your fingers to unscrew it, but I used a 3/4" socket to get it started.

I got the coolant all out, and poured it into one of the distilled water containers, and the coolant did not look as bad as I thought it would, still I am going to flush at least 2 more times.
I used that Lisle Funnel to fill it, and it worked perfectly, I'll never fill a radiator again without it, love it!

I ran it till it got right over 195F, squeezed the upper hose in, and put the plunger in the funnel, then removed it, not a drop came out.
I let it get to 205F and turned the heat on full blast till it hit 216F, now I am letting it cool...
I got all my gaskets and stuff in today, all I am waiting for if the 5W 30 oil, all I have on hand is 10W 30.
Looks like we have rain coming, and should last like 2 days, so I am not sure when I'll be able to begin on the LIM job..

I don't like the way my lower rad hose looks, or feels, it has that feel of a hose starting to dryrot.
I'd change it, but to be honest I am not sure how I'd get at the clamp on the lower part, the part you need to squeeze is facing the ground, and even if I jack the car up, and put it on jack stands, I am not sure if I can get to it then because of that plastic baffle that I cannot totally remove..