Spider Mike's truck was a well-worn Diamond T 921
of late 50's/early 60's vintage. The truck was a later
921 and featured the White Motor Company's
Autocar cab, sometimes referred to as the "Driver
Cab" or "family cab" for its use across multiple
brands of trucks owned by White Motors. The truck
likely had a NH220 Cummins or similar naturally
aspirated Cummins engine.
It has been noted by those close to the production
that of all the trucks used for the movie, this truck
was the most troublesome and was broke down
more than it was operating. The Bruhn Sand and
Gravel company shops in Logan served as the
repair facility for those trucks that couldn't be fixed in
the field. The Diamond T supposedly spent a lot of
time in those shops.
It was rumored to have been seen some years after
the movie in an Albuquerque area salvage yard.
The rumor that the truck still exists today in Canada
is highly implausible as the story of how it ended up
there is not supported by several of the people who
were cited as having owned it after the movie.