sony back up camera replacement

I have just bought a 2001 Winnebago adventurer that came with a Sony back-up camera system as original equipment I think. The monitor is still in place and appears to work(will power up and show static). The camera is missing and I am looking for a replacement. I haven't had any luck finding a direct replacement yet. Does anyone know if any is available anywhere and if not will another brand work in its place. I found a cable adapter to upgrade to a Voyager system and use the original cable that is in the coach. Will just adapting the Voyager camera work with the sony monitor if it can be hooked up with the adapter? The monitor is model no# ssm 721amr. Thanks for everyones help, Keith