So many differences. CSTs are the top of the line optioned trucks (up to '70), whereas the C-10s are usually fleet trucks will few options. Of course the options varied with every truck based on what they were ordered with. Check the SPID (sticker on the inside of the glovebox door) to see what options came on the truck. In your buddy's case the CST will be list here.
Of course I'm not the "knower of all" but I have learned these things over the time I've had my truck. The real experts will probably give you more info. Hope this helps...
