1968 Dodge Seagrave Fire Truck.. never seen one before..

Sounds like the words of a fireman? I was for 33 years. I started driving a long nose Howe. 610 cu in straight 6. It had two complete ignition systems in case one failed. Non synchro transmission, if you missed a shift you had to come to a almost stop and start over. Those were the days when you could ride tailboard!
Yep, I did 33 years also!
My dad did 36, started his career in 1956, and drove the old 'Chain Drive' Ward La France, open cab with the gear shift on the running board. Like you said, he had to double shift, into neutral, then into the next gear, to slow the shaft speeds, otherwise you grinded, no synchros.