The throttle cable on all AD series truck is just that. It's a manual control for the throttle on the carburetor. You can use it to increase the engine speed while stopped for warm up, or I suppose you could use it as a rough cruise control, although I wouldn't recommend the latter.

You should go into your profile and set up a signature that will show up on all your posts.I had to go to your previous posts to find out you have a 1949 1-Ton.
It should include your truck info (year, size, etc.) and anything else you think is relevant.
To do that, click on your username on the upper right of this page, (or any page when you're logged in) and select "edit profile."

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.