You can trust me too.. it's T9..Though a T8 WILL work [slightly loose tho]
The difference is very small, but it is T9 Torx.. for the rotor screws..

 

Trust you, aye? Someone, on a different forum, also posted the same T8 answer. I bet I could fit a T7 in there as well. Tell me, what are the odds GM, er Mitsubishi, used two different size drive head screws in the opti? Do you believe/think a post would be made stating it is a T9, if it didn't fit? Either more than one size drive socket was used, or someone is too clutsy, to align and fit into the socket, the T9. At this juncture, I'd prefer to hold out, against respectable odds, and think possibly... two different sizes were incorporated, for that retaining screw. BTW, the one(s) I've disected, used the T9.

 

well im finished with my project trying to make one good opti out of two bad ones. im going to put it on the car now. i hope it works.

 

Experience has led me to believe, that while some will put 250k miles on a stock opti, once it goes, it will probably go again. This is because, like shoebox said earlier. Opti's usually go bad because of outside issues.
Bottom line, if your opti goes bad, replace it and get a coilpack setup, or replace it and get an electric water pump and pray that you fixed the leak.

 

neither opti is totally shot, one has a bad optical reader. i just swapped the bad one out.

heres a dumb question. before i put the water pump back on i should first fire the car up to make sure the opti is on correctly. the car will run without the pump on?

 

Some people do that. Give it a shot.

 

I wouldnt have it any other way!