I just did this job yesterday. I had the (not so) bright idea that I would use a piloted countersink to do the cutting. I drilled a 14mm bolt for the 1/4" countersink pilot to run in and then cut off a piece of the bolt with the 1/4" hole to thread into the split ring (or whatever they call that ring in the torsion bar tube). Anyway it did not work as planed and I won't go into more detail.
I then used my die grinder with a carbide burr. I left the short piece of 14mm bolt threaded in the split ring and smeared grease over the opening to catch filling (which works very well). I taped some paper around under the torsion bar tubes to catch flying grease and filings. The job was easy and quick. The clean up took as long as the cutting. I don't have any pictures but the rusult looks like the others that have posted photos to this thread. I just guessed at the amount to cut and gave it another 1/4" or a little more slot length.
I used a conical burr (looks like a sharp pointed pine cone) only because I did not have a flat bottom burr. As it turns out I think this might be the best choice as the cone shaped end gave better access.
Does anyone have any updates to this post? Do you have to perform a new allignment after this? What is pro/con of this vs dropped spindles. Obviously, this is cheaper.
57 356A
68 912
73 911S
66 Land Cruiser FJ45LV
71 Land Cruiser FJ40
79 450 SL