From what I see is just a standard tv swing mount. Available everywhere. Just google tv swing mount and find which one you need for the tv you plan on using it for. Hopefully this is what you are asking.
Are you looking to attach this this swivel mount to the block you showed earlier or are you simply looking for a swivel wall mount?
The swivel model you referenced doesn't seem to have a wall attaching plate.
It seems like it would mount/latch onto something already attached to the wall. (hence the question about your current block)
Two years back I had to replace my front TV. Went much bigger and wanted flexibility and utility. I bought the exact mount you want to upgrade to. Can't recall if I got mine at Wal Mart or Best Buy. Did not find it online. Just did a quick Amazon search and did not see it either. I love it since I can easily slip off the 30" TV while traveling.
2011 Sunseeker 3170DSF
2002 Honda CR-V
"Do not mistake my benevolence for weakness."
Remember that RV interior walls ain't like those in houses. No matter what you buy you will need to find a way to support the mount from behind so it doesn't rip out of the wall. If you have access to the back of that mount position then a small piece of plywood or steel/aluminum is advisable as a backing plate.
Lockable on the road.