If it is a matter of just using passive Beovox you only need the mcl 2 A.
There is 3 types of mcl 2 link boxes:
MCL2A For distrubtion of all sounds through passive Beovox and control the system from linkroom. Type 2045-2047
MCL2AV for active speakers. In order for using independing volume control you must use a MCL2P. A Beocord and Beogram cd can be connected too.
MCL2AV X-tra TV kit. For connecting a Beovision and a Beocord/Beogram CD.
You can use 4 units connected together. If more is needed you need the Expander box too.
The MCL2A comes with a tranciver and a relaybox. These can be connected together with other MCL2 type boxes like the MCL2A and MCL2AV.
An mcl cable is going from the Beomaster to the link box and if there more boxes in the setup you put mcl cable from box to box.
The MCL system can be installed all over the place. It's just a matter of locating the parts. They do come up often on ebay and this site too.
Be aware that with each MCL2 you need a pair of speakers or in the case of a MCL2AV X-tra tvkit a Beovision with AUX link.