Replace sides of Intermountain 1937 AAR boxcar to model a Great Northern 4400 series rebuilt box car. The Intermountain box car is desireable for this modification because the ends and roof are not attached in the kit. Undecorated kits are available from Intermountain dealers. See photos showing where to cut and where to align the new sides. Add ladders and other details from kit. One ladder needs to be cut down. Add latching details to doors.