Here's some bacground info on this truck that Jake included:

This was on my truck from the previous owner.

Ashton Chargois
Licensed Master Plumber
(small print you can't read stated"
"S and W B of New Orleans
License #30

The history behind the license is that he was the 30th. licensed plumber after WWII.
He was discharged out of the Navy in 1946, and that was the first year they started a license requirement.
Now they number into the thousands.