I read that before about the posi option. It looks like a Dana 44 rear in the pictures. Maybe it is a very late 58, or who knows. The truck is about to sell on ebay right now. You don't see this setup too often but I don't really don't want to dump $1500 plus into a parts truck.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=320347157733&sspagename=STRK%3AMEWAX%3AIT&viewitem=
1959 Apache 3200, Standard Cab, Big Window, Fleetside, 235/3spd, Original Paint
1964 C20 Standard Cab, Fleetside, 283/Power Glide, A/C, Pwr Steering, Pwr Brakes, NoSpin | 
