What size nut is this?

[sideSHO]

Hey gang.
Missed something rather important on my clutch job.
I left the nut off the pinch bolt that holds the strut to the hub.
I went to Autozone and they could'nt tell me what size.So do you guys know?
Also
I've read that there is a circlip on the drivers side axel.I know I did'nt take one off,but I'm not sure if one was ever in there.How important is this circlip?
Could this cause the slight slack I have at highway speeds in the drivetrain?
Thanks for all the help.

 

[Ishodu]

If you are talking about the pinch bolt that holds the strut in there is no nut it is a threaded hole. Unless some one has drilled it all out then it could be about any size in that range.

 

[SHO Type U]

Try a 3/4", take it from there.

 

[UnsungZero]

just find a new grade 8 or 10.9 nut/bolt combo that fits

(if it's been drilled out)