What's the top speed of a truck like that?
Judging from the picture of the speedometer, which tops out at 60 MPH, I'd say the top speed,or at least top sustained speed is in the 40 - 50 MPH range.
Note: often you will see much more modern vehicles with an 85 MPH limit, this was due to gummint meddling in an attempt to keep us in line, speed-wise.
In this case, the maximum or cruising speed cannot be reliably determined from the speedometer markings.
from Wikipedia:
On October 1, 1980, in a regulation that also regulated speedometer and odometer accuracy, the
National Highway Traffic Safety Administration (NHTSA) required
speedometers to have special emphasis on the number 55 and a maximum speed of 85 mph (137 km/h). However, on October 19, 1980, NHTSA proposed eliminating speedometer and odometer rules because they were "unlikely to yield significant safety benefits" and "[a] highlighted '55' on a speedometer scale adds little to the information provided to the driver by a roadside speed limit sign."
I believe that since then this silliness has been rescinded, although I've heard that speedos are required to lie to us by exaggerating our true road speed; does anyone have better info on this?