I have spent a couple of hours attempting to hunt down this question specifically in CO, sorry if It's been posted prior. I have seen the response relaying GM mechanic, etc, but I've not found it to be that easy. I am actually in Commercial Industrial/Retail with dozens of auto related clients and no one can/will do this work, mentioning the specific engine type.

03/17 engine started going out, (awful metal clanking) mechanic said just block rebuild and he could do it. He had it for 6MO, refused to call me back and hid it off the property -had to get a civil assist to get it back. "Runs" now, (supposedly he rebuilt everything) but shakes/dies at stops unless I keep the gas going, loud ticking noise when I accelerate, temp gage is almost the red zone (stops at the line just before it). I have no idea what the following means, but when I had the diagnostic ran it was explained to me as "did not use a CAM lining tool, timing is off, he broke and welded the manifold, radiator is cracked and he did not put oil or coolant back in". (I had it towed to maintain chain of possession, so did not drive it without oil luckily.) They patched it up to hold me over, but say I need to replace it again, but they also cannot do it. Trying to avoid this scenario again and want to be sure nothing simpler that can be done. Any suggestions/other repairs/rebuild vs replace/shops in the Denver/Springs area would be appreciated more than you can imagine. I still love my H3, just need to get him back in shape!!