Side topic but if your interested in APRS as I am but don't want to spend big money our would like more flexibility from vehicle to vehicle then check this out:
Blutooth TNC from Mobilinkd:
http://mobilinkd.myshopify.com/products/bluetooth-kiss-tnc
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ARPSdroid app; use your android tablet or phone as the UI, GPS, text input, mapping/display tool etc.
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Any 'ol VHF radio, I'm thinking a Motorola Maxtrac commercial radio would be cheap, powerful, and high quality.
IMO you could put together a superior APRS set up due to the vastly better UI on android vs. trying to input data to a radio face. Android can function as the map display, input screen, GPS receiver, and output screen. The gear left in the vehcile would be of low value to a thief, you could build multiple RF set ups and move the mobilinkd and android from vehicle to vehicle or vehicle to backpack, etc. etc.
I haven't put this together yet but I'm quite tempted to try it out.