The 15689 is an Aftermarket 12V Slotted Clockwise Single Post Terminal Motor. This motor is used on the early E60 plow pumps. The Later motor has 2 Post Terminal and is the 15841. 

Alternate Part Numbers: Diamond: 15689; Fenner/Fenner Stone/SPX: 2529-80, 2529-AC, 2869-AB; Iskra: 11-212-981; Lester: 10710, 160-848; Meyer: 15689, 15727, 2529AB, 2529AC, 2869AB, M15727; Prestolite: 46-4196, MUE6209, MUE6209S, AMT0354, 155-9865; 51052; 1306007, LMY0001, W8991, ATM0354