[EricH]

The AM trannies are COTS MECHANISMS. From the 2008 manual, Section 8.3 Definitions:

COMPONENT – A ROBOT part in its most basic configuration, which can not be disassembled without damaging or destroying the part, or altering its fundamental function.[examples, including bolting a frame together]

MECHANISM – A COTS or custom assembly of COMPONENTS that provide specific functionality on the ROBOT. A MECHANISM can be disassembled (and then reassembled) into individual COMPONENTS without damage to the parts.

Unfortunately, your interpretation seems to be correct. (Note: If it isn't the correct one for the 2009 rules, then we'll both be highly annoyed.)

As for the reuse of parts: For certain parts, it is allowed under the 2008 rules (e.g. using the same two unmodified AM trannies would be legal, provided that they conform to all current rules). See 2008 <R26>.