What lvl do I find s ranks

[DUN]

Im lvl 53 and the only s rank I have found was a dreamcast.

[Chuck_Norris]

You need to be more specific. I've gotten S ranks in missions as low as B rank.

[DUN]

Is there a site like this one but for the portable that shows drop charts

[DarkRealm]

Take your take and read through here
http://psupedia.info/PSP:Phantasy_Star_Portable

Then for the drop chart (not complete)
http://www.gamershell.com/faqs/phantasystarportableweaponfaq/0.04/