I recently had my engine replaced in my 93 Blazer, a V-8. Last night while driving a major exhaust leak started out of nowhere. I looked at it today & I see something fell out of a threaded hole. My mechanic is in Fla & the other people I know who might be able to help are also MIA at this time. I'm not a mechanic but I will try to explain it & maybe somebody here can help me??? Above the 2 mounting bolts on the section of the manifold closest to the front on the driver side there is a section that rises up. There is a 3\4" threaded hole there that had something in it before last night LOL. I looked at the passenger side and that section also has the higher section, however it is completely sealed with no hole, or bolt inserted in a hole there to make a guess as to what was on the driver side. Any ideas? Can I just put a bolt in there to seal the exhaust leak until I get it to the shop for them to look at? Besides waking up everybody that may be sleeping in their houses near where I'm driving, is it OK to take short trips with that 3\4" exhaust leak, or could that create other problems with the engine? Thanks for any help.