MF 20 Exhaust Manifold Studs...Kinda Long

I'm sure that what I am about to reveal is not news to most on this forum, but if it might help someone, I thought I would put it out there.
This weekend, I got my 20 running for the first time in a couple years, and it had a terrible exhaust leak (the rear gasket was....gone). No big deal, removed the manifold, went and got some high temp gasket material, cut new gaskets etc. I decided since I had everything apart I would change the studs. (This decision was helped along by the fact that I broke one of the studs during removal.)
After 2 days of soaking the studs with penetrant each time I walked by, I got the vise grips out and proceeded to remove the broken stud. This is where it got interesting....
Apparently, the holes in the head are tapped right into the coolant channels in the head, because when I removed the stud, I got a cold, slimy green surprise!! Of course, the shock of 17 degree antifreeze shooting out at me caused me to drop the stud, which rolled under the tractor. By the time I looked around, grabbed the nearest thing that would contain the coolant (an old ice cream bucket) and shoved it under the hole, I have no idea how much coolant hit the floor, but lets just say I need to restock on floor dry!!
I planned on draining and flushing the cooling system, I even have the new coolant in the cabinet already, but I guess I got an early start!!
I learn something new every day....

Nice one! Another little thing concerning exhaust manifold hardware, a work mate of mine years ago, and I can't remember the tractor he was working on, found an exhaust manifold bolt broken. He extracted the bolt with an easy out, found a new bolt in a box on his bench, screwed it home-all good, but when he started the tractor it only ran on 3 cylinders. The bolt he used was too long and the hole was threaded right through to a push rod tube, the bolt had hit the push rod and bent it!