Well Jon... I can help extra special if I know which head (front or rear).
I can tell you right up front, you'll probably not break off the bolts, and using the impact won't be an issue those bolts are plenty tough.
But right up front the issue you'll most likely encounter will be the threads those bolts go into. Unfortunately due to the very soft castings (sand cast) of our cases, those threads just plain ol' fall apart or pull out. So prepare yourself to be installing inserts.
Some owners have had luck on salvaging those threads, but not very many. I tackled them with all intent of be gentle beginning to end, and they just pulled out... ...
Give me a little more info, and I can help you thru it....
Bruce
