Ever see a Mail Bus like this one in the 60ies?

[GOPAPA]

There was one of these mail sorting busses on highway 30 between Portland Oregon and Astoria Oregon ,,,and one winter one slid sideways down the icy highway and almost wiped me out going to work..

The Bus had a mail sorting side with in the bus so when they stopped at all the little towns with post offices the mail was sorted and handed out to them and also picked up the same way when traveling back from Astoria to Portland

Yes thats a gun on the mail sorters side