The drawing for the 25:1 Metal Gearmotor drawing shows the mounting centers to be 15mm, it is actually closer to 13.5mm or 17/32"
Yes, you are right. The distance between the center of the mounting holes for the 25:1 metal gearmotor is 13.5mm instead of 15mm as shown in the drawing.
We are not able to change the drawing right away because we got the drawing from the manufacturer. But we have put a note on the product page.
Thanks for letting us know.
–Fang