There's nothing out of place whatsoever with the truck within the movie's time period. The Market Crash happened in 1929. The movie was 1926 and this ride has been said to be about a year after the movie, 1927 (the photo of placing the tiara atop the water tower has 1927 written on it).
Trucks like these were very much commonplace on large farms during that era. Well before that year in fact.
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Out of place in Frontierland as a whole, then I agree. But since you specified the PATF movie and its time period, no it's perfectly reasonable in that context.