You may want to try the GPS 18 OEM:http://www.garmin.com/products/gps18oem/index.jsp
The nice thing about it is that it has a bare wire cable. That way you just have to put the mini plug on for the data and wire up a power supply (the 18 PC must have a sigarette adaptor on the end).
However, you may want to get a full blown GPS with a display, maps, etc. For one thing, it is a lot more useful as a general navagation aid. And, the D700 sends NMEA waypoint data back to the GPS for display. I've been in situations where I see a station pop up on my map and look around for the antennas. Great fun.
I've been using a th-d7 and a tm-d700 for a few years now, and overall think they are a very good design for mobile aprs use. I've considered a puck type gps for my d7, but for the reasons listed above, I thought it better to go with a display-type GPSR. The cost differences are minimal these days. However, Garmin only has one cable type that is available in bare ends, the round 4 pin connector. I think this is because it is designed for recievers that can take 12Vdc, so they figure people won't be frying their equipment. I've modified several cables for my Vista and Foretrex 201 and haven't had any issues. My Vista sits on the dashboard, wedged in under the windshield and it maintains a lock all the time, if that is a concern going with the puck mounted outside.