Most of the pumpers I've seen, even current ones, are equipped with a big set of wheel chocks which are used while pumping water. It's just one more safety feature to assure the truck doesn't "go walkabout" while it's on the job!
The only downside to a Brownie trans is the need for a second shift lever, and since most of them aren't synchronized, you'll need to get good at split-shifting without using the clutch. It's an acquired skill, but once you get the hang of it, it's actually faster than shifting with the clutch in the mix. A 5-speed becomes a 15-speed with the Brownie involved, and you'll also have 3 ratios to choose from in reverse.
Jerry
