I found this one outside a hotel where I went to a convention last weekend, the Marriott at Eagle Crest in Ypsilanti, off South Huron Street and James L. Hart Parkway. Unfortunately, the contractor name is illegible. It is [something] Concrete, and the style is extremely similar to the Audia Concrete stamps from the same year that I have found in Lansing. Audia is located in Milford, not too far from Ypsilanti, but I am pretty sure this is not them, because I thought I could make out an F in the otherwise illegible name. It is probably another contractor who bought their stamp from the same supplier.
Unfortunately I could not find another stamp in the expanse of concrete in front of the hotel so this one will have to remain a mystery.