Can someone tell me if the cranks on a Trek 400 have 9/16 threaded petal holes . I am thinking about buy this bike but wish to replace the petals with a petal that has SPD cleats. I understand that there currently are two "sizes" of petal threads 1/2 and 9/16. But I don't know what the standard size was when this bike was marketed. Mid 80's I think.

Thanks