<ACCESSION-NUMBER>0001193125-18-043949 <TYPE>SC 13G/A <PUBLIC-DOCUMENT-COUNT>4 <FILING-DATE>20180214 <DATE-OF-FILING-DATE-CHANGE>20180214 <GROUP-MEMBERS>CARL P. KAUFMAN <GROUP-MEMBERS>JOHN S. OSTERWEIS <GROUP-MEMBERS>OSTERWEIS CAPITAL MANAGEMENT, LLC <SUBJECT-COMPANY> <COMPANY-DATA> <CONFORMED-NAME>Blue Bird Corp <CIK>0001589526 <ASSIGNED-SIC>3713 <IRS-NUMBER>463891989 <FISCAL-YEAR-END>0930 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>SC 13G/A <ACT>34 <FILE-NUMBER>005-87838 <FILM-NUMBER>18606835 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>3920 ARKWRIGHT ROAD <STREET2>SUITE 200 <CITY>MACON <STATE>GA <ZIP>31210 <PHONE>478-822-2801 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>3920 ARKWRIGHT ROAD <STREET2>SUITE 200 <CITY>MACON <STATE>GA <ZIP>31210 </MAIL-ADDRESS> <FORMER-COMPANY> <FORMER-CONFORMED-NAME>Hennessy Capital Acquisition Corp. <DATE-CHANGED>20131017 </FORMER-COMPANY> </SUBJECT-COMPANY> <FILED-BY> <COMPANY-DATA> <CONFORMED-NAME>OSTERWEIS CAPITAL MANAGEMENT INC <CIK>0001007524 <IRS-NUMBER>942871718 <STATE-OF-INCORPORATION>CA <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>SC 13G/A </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>ONE MARITIME PLAZA <STREET2>STE 800 <CITY>SAN FRANCISCO <STATE>CA <ZIP>94111 <PHONE>4154344441 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>ONE MARITIME PLAZA <STREET2>STE 800 <CITY>SAN FRANCISCO <STATE>CA <ZIP>94111 </MAIL-ADDRESS> </FILED-BY>