445gsd

I own an 04 Silverado and 05 Yukon Denali XL. I just had the OEM 6.0 Vortec replaced in the Denali (~250,000 miles) with a Jasper re-man, at what I consider to be a reputable shop. I picked the Denali up Tuesday, pulled out of the shop parking lot onto a highway (was NOT ******* it) and things went nuts - I started hearing all sorts of clatter, motor was hesitating/missing, check engine light started flashing, and had trouble making power. Turned right around went right back to shop - drove the vehicle about 1-2 miles total as I was on 2 lane divide HW and had to turn around to get back. Arrive back at the shop and the owner came out to look at issue. Opened the hood the clatter was loud enough to almost be uncomfortable to listen to at that point. He said sounded like a lifter.

I get a call yesterday evening saying that it "was only a rocker that Jasper forgot to tighten all the way" and that it had been corrected and was good to go. Also was told it would not affect the engine life and it wasn't a big deal. They stated they were "very surprised" as they'd driven it about 30 miles and had seen no issues. (I believe this based on mileage) I will say that it had sat 4 days at the shop between when they test drove it (Friday) and I picked it up the following Tuesday. (this was because they were doing some other odds & ends for inspection after the test drive, and it wouldn't be done until Monday, then I got stuck at work that Monday afternoon and couldn't go pick it up until the next day - Tuesday)

I pick it up again this afternoon and am wondering if there is anything I should be looking for? I have to say, I'm more than a little concerned. I've never had an engine replacement done before and to literally not make it out of the lot is not a good first impression... I'm also concerned about whether the issue could have harmed the engine or shortened its service life? Finally, I had the o2 sensors on the exhaust system also replaced while at the shop. Could the rocker issue have caused anything down-stream that could affect them? Like oil blowing into the exhaust (because of the rocker issue) and fouling them? Supposedly it is good to go with no CEL - but having just paid for them to be replaced, I don't want to worry about them having life span issue either.

Should I accept the truck with what happened, or possibly ask for the engine to be swapped with one that didn't come from Jasper with a problem? I'm not trying to be "that guy" but for ~$10k I just don't want to end up screwed.

Thanks for any advice!

Calvin