The stud that my shifter know screws onto has had boogered threads as long as I have had it (I bought the shifter assembly for my auto->manual conversion). It had gotten to the point where the knob would become loose and wobble on the stud itself. Certainly not a desired effect while driving. I tried using a die to fix the threads but it was clear that the stud was beyond saving. Shown here is how I fixed this problem. You can too!

Here are the things you'll need:
M8x1.25 tap and tap handle
17/64" drill bit
several smaller drill bits to work your way up to the 17/64"
blue locktite
power drill
2 M8x1.25 nuts
2 13mm wrenches
a magnet (to catch filings and drill chips)
a hacksaw
a file
M8 stud, ( I believe mine is either 40 or 42mm. The 46mm stud had an unthreaded section in the middle which was undesirable)

Here is a picture of the basics:
Shifter 014 (Copy).jpg

Here is my cross threaded and damaged shifter stud:
Shifter 004 (Copy).jpg

First thing is to cut it off, and use the file to flatten the surface:
Shifter 006 (Copy).jpg

Next drill a hole in the center with a small drill bit, went down about 3/4 of an inch; about half the length of the stud:
Shifter 007 (Copy).jpg

Work the hole larger incrementally with larger bits:
Shifter 008 (Copy).jpg

Finally the hole is 17/64" and ready for the tap:
Shifter 010 (Copy).jpg

Start tapping the hole slowly with the tap:
Shifter 011 (Copy).jpg

Jam the 2 nuts on the stud, put blue locktite on the stud, and thread it down into the shifter:
Shifter 015 (Copy).jpg

Remove the nuts from the stud and the new stud is in! (actually you can still use one of the studs as the shift knob adjustment nut):
Shifter 012 (Copy).jpg

Put the shift knob back on and you're good to go!:
Shifter 017 (Copy).jpg