I got a chance to check the FJ Cruiser brakes on the HZJ73 today. Short answer... in my opinion the FJ Cruiser rotors, brake pads and calipers will work on my 73. The rotors are the same size and the brake pads are also the same size. The calipers on the HZJ73 are mounted on the front of the rotor, whereas the FJ Cruiser are mounted on the rear of the rotor. In order to make the calipers work you will need to swap them side to side in order to keep the bleed holes at the top of the calipers. I believe the FJ Cruiser calipers will work as well, but I need to do a little more research caliper part numbers.
The parking brake is a crap shoot right now as I would need to take the hub off the FJC and remove the shoes in order to compare the setup. The braking material on the FJC shoes is about 3-4mm narrower than the HZJ73. The material length is also similar (see pics). My e-brake on the 73 is fine, so not plans to change it now, but when it needs replacing I will first try the FJC setup as I think there is a good chance it will work.
I am going to order a set of FJ Cruiser rotors (part # 42431-60201) and I will run them on my HZJ73. I'll report back any issues that I run into, but I do not expect any. Talking with Kurt at Cruiser Outfitters he noticed that the FJ Cruiser part number was reverse superseded by the current part number 60180. I'm posting this information in case anyone else might find it helpful, but please do your homework and make sure you order the right parts for your truck as this is my experiment.
As few pics (ok a lot of pics) to help...
Here is the 73 brake setup. Note the locations of the caliper is on the front of the rotor.
Here is the FJ Cruiser brake setup. Caliper on the rear of the rotor.
Here is the HZJ73 caliper.
Here is the FJ Cruiser caliper. I need to do some searching on the part numbers, but it is the same size as the 73 calipers.
HZJ73 rotor measurement across the front is the same at the FJ Cruiser.
FJ Cruiser rotor measurement across the front.
HZJ73 braking surface... again same as the FJ Cruiser.
FJ Cruiser braking surface...
Comparing both rotors... the HZJ73 is the rusty one...
The HZj73 has been turned down once or twice and is about 1mm thinner.
HZJ...
FJC...
HZJ73 rotor on an FJ Cruiser...