Of course, went to count and got to 7 and oh crap where's the eighth one My guess is either one of my 4 kids grabbed the thing or it's somewhere in the mystery garage blackhole...

Now, to find a replacement (or probably 8 replacements as I was going to de-rust and polish or paint, so now just assume get 8 brand new ones that are already nice and shiny). Ok, so after research, looks like these were single use anyway, so probably explains why they were loose and all eight should be replaced..

Does it have to be the helicoil type or can some other replacement suffice? And what are the recommendations as (now that I've actually researched a bit) a big problem is with the manifold nuts loosening due to the heat cycles (total sense)?

Thanks in advance

 

I would use the helicoil style nuts if available, they are less prone to seizing. I have used a standard nut when a full set of original nuts was not readily available.