Wuttermelon@MrOGDEN Yes, as long as the existing stack is removed and a hole drilled for this part. Some of the prototype GP units had differing height spark arrestors though so it may need a little bit of filing near the mounting base to match.
Wuttermelon@adraggin The spark arrestors were originally modeled for the unique MKT 401B project per a customer request. However I know these are not common to the MKT, but more frequently seen on MP locomotives.
Wuttermelon@atsfrocks This was designed for a customer to be used with Walthers DL109s, however in this case, specifically for an EMD re-engined Rock Island model (621). The circle cutouts are designed to fit Gold Metal Models etched fan grills for GP units.