Help! Needing a 2SC2312 final

Yes, the central hole has a threaded screw and nut holding it fast to the rear of the case. I am a bit confused though does the heatsink compound go between the insulator and the transistor, or the insulator and the case wall, or both?

 

i would put it between both

 

I figured as much, thanks for the confirmation WA4GCH Prosit!