Note, there is no client application (known as the legacy c# client) for vSphere 6.5 or 6.7. vSphere Client 6.5 and vSphere Client 6.7 It’s worth noting that the vSphere client tends to be backwards compatible, you can check this out using VMware’s interoperability matrix.
VMware vSphere Client 6.0 Update 3: VMware-viclient-all-6.0.0-5112508.exe.VMware vSphere Client 6.0 Update 2a: VMware-viclient-all-6.0.0-4437566.exe.VMware vSphere Client 6.0 Update 2: VMware-viclient-all-6.0.0-3562874.exe.VMware vSphere Client 6.0 Update 1: VMware-viclient-all-6.0.0-3016447.exe.VMware vSphere Client 5.5 Update 3: VMware-viclient-all-5.5.0-3024345.exe.VMware vSphere Client 5.5 Update 2: VMware-viclient-all-5.5.0-1993072.exe.VMware vSphere Client 5.5 Update 1b: VMware-viclient-all-5.5.0-1880841.exe.VMware vSphere Client 5.5 Update c: VMware-viclient-all-5.5.0-1745234.exe.
The question of where to download the vSphere client, including previous versions, comes up now and again.