The second pair of numbers in the sequence is the body type. They break down like this-
02= chassis and cowl
03= chassis and cab
04= pickup (stepside after '58)
05= panel
06=suburban with doors ('55 and later)
07= canopy(pre '55)
08= platform
09= stake
12= chassis and windsheild
16= suburban w/ endgate
24= Cameo
34= Fleetside
42=Dubl-Duti chassis
45= DD walk in delivery
53= chassis and cab 4x4
54= stepside 4x4
84= Fleetside 4x4
55= panel 4x4
56= suburban w/ doors 4x4
66= Suburban w/ endgate 4x4
59= stake 4x4
I only covered the 1 ton and lower trucks, there are similar designation brakdowns for the big trucks, too.
And yes, they did make 3800s in '50. The 31,36,and 3800 designations actually date back to the Art Deco body.
