Hi James,
There is no specific image for Central manager. You can select the mode when you install WAAS for the first time --> whether you want it to act as central manager or application acceleration. You can select any of the universal images. Universal images can be used for Application accelerator or Central Manager but Accelerator images can only be used for application accelerator.
Further details about various WAAS images on CCO can be found here:
http://www.cisco.com/en/US/docs/app_ntwk_services/waas/waas/v443/release/notes/ws443xrn.html#wp90088
You can download the WAAS images under Cisco --> Support --> Downloads --> Browse all categories --> Products --> Application Networking Services --> WAAS --> WAAS software.
Regards.
PS: Please mark this as Answered, if this answers your question.
