I can only offer my experience and a link to my thread from couple years ago. It has photos that confirms that you do indeed have to pull heads but don't have to lift motor. The heads were pulled to make sure they didn't warp.
http://forums.trailvoy.com/showthread.php?t=75049

 

replaced exhaust bolts 5.3

just had my exhaust bolts replaced on my 5.3 trailblazer ext 4x4. mechanic was able to lift the engine one side them the other to change them I had 3 busted (two on one side and drivers rear on the other. replaced all with ss grade 10 hope I'm done with this. Cost $500

 

I also had 3 exhaust manifold bolts that were broke on this 2006 TB V8 I just picked up. There were 2 on the passenger side- the one closest to the front and the one closest to the firewall. I was able to use vise grip pliers to lock onto these and remove them. I had to remove a lot of "stuff" just to gain access. On the driver side, the last bolt closest to the firewall was broke off inside the head. I had to remove the head & drill it out. Now that everything is back together, I have a very faint "tick" that remains. I'm thinking (hoping) the exhaust manifold is warped and a new one will fix it. I did use new exhaust gaskets on both sides.

 

exhaust manifold bolts

just a quick update- so far no new exhaust leaks and we are now at 146000 miles. still love the 5.3. pulls strong

 

PTOwen 25, I recently had to rebuild my transmission and one of the most difficult situation I came across was having to remove the catalytic. Mind you I have a 5.3 V8 Trailblazer and I was working on the floor because no access to a lift. Anyhow!! I had to cut 3 bolts off and the other 3 came offrom fairly easy, I had to pay about $80 for 4 bolts and nuts from the dealer because I wanted to do this job the correct way and not buy something that was not going to work. Believe it or not the bolts that I cut and the rest of the bolts came out easier than I expected. I took one of the sockets that removes stripped bolts and nut and applied the cordless impact to it and place it on the stud and it came rt out less than a minute. I advise you to hit it with some PB Blast also.

 

PTOwn25 sorry for the typo, I didn't notice how long ago this was sent posted. Lmaoo. I'm sure you fixed that 3 years ago. Lol. I'll be sure to keep a look out on the dates of these posting for the futer. I am new to this forum world so just trying to get the hang of it.

 

It happens to the best of us.

 

You ain't lying

 

nice post