iirc it's like a 17 and a 19, annoying, you need at least 4-5 sizes for the job iirc, I've gotten lazy a few times and just used an adjustable wrench.
Make sure you have a deep socket for the nut on the SPC bolt, the bolt extends far past the nut so a short socket won't get it all the way on.
I found this DIY that calls out all the tools for disassembly:
http://www.ft86club.com/forums/showthread.php?t=10842
Harbor freight man, save yourself a few bucks, hobbyists don't need lifetime warranty tools imho. Buy the whole set that has the one piece you need, repeat until you have just about everything.
Also I don't know what a struct is, but I'm assuming you mean strut.