Dave,
Here is a picture of the throttle linkage on my '38 1-1/2 ton. I just got around to pulling the manifolds off last night so I could take the picture.
Throttle Linkage The screwdrive is in the position that the throttle rod from the floor board would normally be in.
There are two levers. One (the inner one) has a return spring on it and an adjusting screw (at the upper end) that pushes against the outer arm. This outer arm is connected to the vertical rod that goes to the carb.
Let me know if you need additional photos. I'll be pulling it off the engine in the next few days and can take better pictures of the individual pieces if you need them.
