def is_combination_truck(df):
    """Return if vehicle is a combination truck, per NHTSA convention."""
    yr = df['YEAR']
    body = df['BODY_TYP']
    tow_veh = df['TOW_VEH']
    return yr.between(1975, 1981) & (body.isin([57, 58, 59]) | body.isin([
        53, 54, 55, 56, 60]) & (tow_veh == 1)) | yr.between(1982, 1990) & ((
        body == 74) | body.isin([70, 71, 72, 75, 76, 78, 79]) & tow_veh.
        between(1, 5)) | (1991 <= yr) & ((body == 66) | body.isin([60, 61, 
        62, 63, 64, 71, 72, 78, 79]) & tow_veh.between(1, 4))
