I was obsessing about my fan clutch, it had a stripped hole where the fan bolts on. Finally today I decided to just do it, drilled the hole (and another one that looked kind of shaky) to the size for the Helicoil tap, then tapped the holes. Now these are blind holes so I didn't drill them any deeper for fear of letting all the goo out, and the holes are real short, so I just cut the Helicoil tap off after the taper and put just a hint of a chamfer on it, then retapped the holes all the way down. Works like a charm. I have to buy another Helicoil kit now but a heck of a lot cheaper than finding a thermostatic fan clutch for a Studebaker. So put this in your bag o' tricks for fixing old stuff, you can make a "bottoming Helicoil tap" and it works fine. Hardest part was drilling the holes, honestly. All four bolts torqued up real nice, no problems now.
nate