Hi,
Check out: http://www.cisco.com/en/US/partner/docs/voice_ip_comm/connection/8x/release/notes/861cucrn.html
Statement from the above link:
If you need a MCS 7835, you can buy the MCS7835-I3-K9-UCC2 server, which comes preloaded with Cisco Unity Connection 8.5. Add 2 GB RAM to the server (MEM-7835-I3-2GB=), and upgrade the software to Cisco Unity Connection 8.6
But checkout discussion: https://communities.cisco.com/message/71011#71011 as it may no longer be offered or not for much longer.
I personally would go a UCS server as the pricing is not really different you get more hardware power then you can migrate other UC apps onto it at a later time.
