Step1: Pick a cab size; regular, super or crew.
Step2: 250 or 350? Gasser? You are only showing the 350s, so I assume you are leaning that way.
Step3: SRW, 4x4?
Step 4: long or short bed.
Step 5:GVWR. look for GVWR pkg with payload 0f 3200 lbs or more. Might shoot for something a little higher for crew cab if you often have passengers.
Example: Crew cab, f350, SRW, 4x4, long bed. The GVWR pkg of 10900 lbs (probably a gas engine) has payload capacity of 3890 lbs.
Hope this helps.