Brake caliper bolts

I went to remove the brake calipers from my '91, expecting to find two 13mm bolts holding them on. Instead I find two small 12 point splined bolts. I pulled out my metric splined socket set, and it was smaller than my smallest 8 mm socket. I experimented around with 6 point sockets, and it looks to be 11/32". Does this sound right?

If jeep made a part for the XJ, it was metric. If they bought a part from somebody else, it is pretty good chance of being either metric or SAE. For the brake hardware they seem to have bought from GM and so it would probably be SAE.

2001 uses 13mm hex head bolts. Got replacement bolts and guide pins (Wagner brand) for my son-in-law's 2001 and they were 12-pt 8mm. What a pain (I only had a wrench).

Took them off last night. The ended up being 8mm 12 point bolts. I screwed up in my original post and said I tried an 8mm. It was actually a 10.

Also did my passenger side upper and lower ball joints yesterday. That job is a real pain.