I'm not familiar with that switch or model truck but looks to be a resistor for lower speed and it looks kaput.
At a minimum you could remove it and probably have high speed only. Later replace the broken parts.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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