Will a standard MacBook Pro optical-bay HDD caddy fit a non-unibody MacBook Pro?
The optical drive in a non-unibody MacBook Pro uses a PATA interface, so you would need to go with the MCE or iFixit caddy, both of which use an interconnect board to convert from SATA on the HD side to PATA on the logic board side. 

The caddy on Amazon needs a SATA connection on the logic board side, so it will only work in a unibody MacBook Pro.