I don't know Fred,
I have not driven it in other than granny gear and then reverse. Loading and unloading on the trailer.
But it does have that lockout out toggle.
Could it be a 47 that was sold in 48?
Title says 48, but the motor has been swapped out and there is no way to link the title to the truck.
I truly believe I am the third owner. The second owner bought it in 1952.

You should remember it when you and Leo met up with John and Joe and myself in mid Missouri right before one of the Reunions in KC.
Joe took the picture of the trailer tech tip when I was on the outer road passing you guys.
https://www.stovebolt.com/techtips/trailering/index.html

I'll see if I can get a picture of the gear shift tomorrow.

Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!