As I understand it, the following are required to certify
the Apollo 2001 for APPROACH.
1. The IFR version of the 2001. This has a different
set of circuit boards from the VFR version.
2. A CDI that is in the pilot's view. Only some VOR
CDIs can take an external DC input, so you may need a new CDI.
You might be able to get away with a CDI meter movement from
an old Omnigator if you can find a suitable spot for it.
3. An annunciator panel with a few switches and lights
4. Serialized barometric input. Most installed encoders
and transponders use parallel.

BTW I've been told that the 480 with WAAS does not require the
baro input.

Start saving your dimes for a 480.

--
Chuck Forsberg www.omen.com 503-614-0430
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 FAX 629-0665