Well, as promised here's the Auburn Rubber Company's #533 Fire Engine Assortment. I had to buy a couple of figures to make the set complete but it was worth it. As a fatter-of-mact, I believe my set was a 'put-together' set - one in which there may have been pieces original to the set box, but the remainder were simply extras the seller had and just threw them in. I'm comfortable with the vehicles being appropriate for the set but can't really say what combination of colors were included in regards to the figures - were they all color matched, were the firemen one color and the policemen another??? When I bought this set it actually had a whole bunch of duplicate figures of different colors. I also cannot say definitively when the set was released although I would be comfortable in making an educated guess of late 1950s.
The first photos show the recently acquired figures - Policeman w/Billy Club, and Policeman blowing whistle - followed by the set box and contents.. Enjoy!
This photo was taken prior to obtaining the remaining policemen.