Julie ... are you handy with clip art? If you are, you can find several different CDs, at any store selling computer software, that are loaded with clip art - usually for under $10 per CD. Softkey, in particular, puts out some pretty good collections.
point being that you're bound to find trucks and other equipment in those collections. you can resize them and print them to cut apart as applique templates.
as time goes by, you'll probaby find yourself going back to the same CD(s) over and over again to make templates of other things, too.