Currently, our preferred tracking setup is a Yaesu FT-2600M 2m transceiver and a Kantronics KPC3 PacketCommunicator. The KPC-3's are fairly easy to find at hamfests and on eBay. With the general demise of the 1200 VHF packet networks, there are plenty of these things available, usually for very good prices.
The Yaesu radios aren't quite as easy to find, at least the bargains. However they have a front-firing speaker which is great if your radio is mounted in a portable enclosure. Also, they have a data interface so you can have your TNC fully wired in (Rx audio, Tx audio, PTT) and still be able to hear the received audio on the front speaker. The volume is independent of the audio level being sent to the TNC (i.e. you can turn it up or down, and don't have to worry about bumping the volume knob and crippling your receive capability).
The biggest downside to the 2600's is they haven't been made in a few years, and used is about the only option you have.
The wiring interace cable is as follows:
|Function/Device||FT-2600M DB9 (male)||KPC-3 DB9 (male)|
|Push To Talk||7||3|
Since both plugs are DB-9 Males, be sure to label which side is which. They are obviously NOT interchangable.