These tokens were produced by the motor company Mack Truck to promote their new 'Bulldog' line of vehicles. There are several varying designs for the obverse, but the reverse always has the large 'YOU make the difference' lettering.
Some tokens have two dates, 1900 and 1975. These were produced in 1975 to commemorate the company's 75-year anniversary.
Other tokens have the text 'Non-negotiable GAME TOKEN non-redeemable', suggesting that the promotional tokens were produced with specifications as to facilitate their use as arcade game tokens.
Here are approximate catalog values for these tokens:
worn: less than $1
average circulated: $1
well preserved: $8
fully uncirculated: $30
As you can see, non-worn specimens that have not lost their mint luster are worth considerably more than dull, corroded tokens.
As always, refer to our 'Important Terminology' page in order to properly interpret the catalog values provided on this page.