Kyle,
I always use Don Moen's Ultimate Recycler Page to do the serial number breakdown.

5 = Kansas City, MO assembly plant
R = This doesn't work, it should be F for 1948
K = Series 4400 (1 1/2 ton)
A = Assembled in January
1093 = 92nd truck off the line (sequential numbers start with 1001)

Jeff Nelson

"Beer is proof that God loves us and wants us to be happy." - Benjamin Franklin
"Always do right. This will gratify some people and astonish the rest." - Mark Twain