These are the OEM front upper control arms, or FUCA's for short. We highly recommend these as apposed to adjustable control arms. The 300ZX as a design flaw in the front suspension that causes twisting with compression, causing adjustable arms to come loose! A large rubber bushing is needed to absorb the twist without stressing metal components.
Please be aware that Nissan / Nismo / Infiniti pricing is subject to change.