Pick up some pads from nissan. I used aftermarket pads for years and always had problems with them squeaking. A fellow Z guy told me to use Nissan pads and I would not have that problem. It has been about 10 years now squeek free.
Are they the stock set-up? is it a z or zx? One thing that sometimes tempororly fixes squeek is to take the drums off and clean them out. You should probably check them out though. Sometimes cheap brakes don't last so long. I had some carquest cheepies ($25 for all four) last me about 10k miles. Pretty sad. Also when you do the brakes make sure the rotors and drums are in spec and have them machined. If you don't like squeeks dont get ceremic(sp?) pads, they never shut up. I also do second OEM Nissian brakes, I have never used this in perticular, but in my experance when you go with factory brakes, they work better be it subaru, ford, chevy, toyota whatever they are just higher quality.
What kind of Z is this anyway. If it's like my 78 280Z get rid of those smallish calipers and upgrade to the 4X4 "S-12" 4 piston calipers. I used to have the original calipers on my Z AND I do lots of brake jobs. 30 yrs worth! The original brakes DON'T do the job. They have TINY PADS! The 4X4 upgrade has pads that are 50% bigger.(More like a Honda Accord, sadly enough!) No more squeeks, AND A LOT LESS MAINTENANCE! Even a "brake job kind of guy" HATES to do the same darn thing over and over. Our Z's need lots of stuff all the time and lame little brakes are a ball buster! Norm K.