Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
UTA 70 Class
Table title:
Status
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Number </th><th colspan=1 rowspan=1 > Power Car Name </th><th colspan=1 rowspan=1 > Status </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <th colspan=4 rowspan=1 > Power cars </th></tr>
<tr> <td colspan=1 rowspan=1 > 71 </td><td colspan=1 rowspan=1 > River Bush </td><td colspan=1 rowspan=8 > Scrapped </td><td colspan=1 rowspan=8 > Engines, generators and traction motors refurbished for use in 450 Class </td></tr>
<tr> <td colspan=1 rowspan=1 > 72 </td><td colspan=1 rowspan=1 > River Foyle </td></tr>
<tr> <td colspan=1 rowspan=1 > 73 </td><td colspan=1 rowspan=1 > River Roe </td></tr>
<tr> <td colspan=1 rowspan=1 > 74 </td><td colspan=1 rowspan=1 > River Lagan </td></tr>
<tr> <td colspan=1 rowspan=1 > 75 </td><td colspan=1 rowspan=1 > River Main </td></tr>
<tr> <td colspan=1 rowspan=1 > 76 </td><td colspan=1 rowspan=1 > River Inver </td></tr>
<tr> <td colspan=1 rowspan=1 > 77 </td><td colspan=1 rowspan=1 > River Braid </td></tr>
<tr> <td colspan=1 rowspan=1 > 78 </td><td colspan=1 rowspan=1 > River Bann </td></tr>
<tr> <th colspan=4 rowspan=1 > Buffet cars </th></tr>
<tr> <td colspan=1 rowspan=1 > 548 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Ex MPD buffet </td></tr>
<tr> <td colspan=1 rowspan=1 > 550 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Preserved by RPSI </td><td colspan=1 rowspan=1 > Ex MPD buffet </td></tr>
<tr> <td colspan=1 rowspan=1 > 554 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Ex AEC buffet </td></tr>
<tr> <th colspan=4 rowspan=1 > Trailer cars </th></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 701 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td class="highlighted"  colspan=1 rowspan=1 > Brake First Rebuilt as DBSO 1977 </td></tr>
<tr> <td colspan=1 rowspan=1 > 702 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Brake Composite </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 703 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td class="highlighted"  colspan=1 rowspan=1 > Brake Standard Rebuilt as DBSO 1977 </td></tr>
<tr> <td colspan=1 rowspan=1 > 711 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Driving Brake Composite </td></tr>
<tr> <td colspan=1 rowspan=1 > 712 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Driving Brake Composite </td></tr>
<tr> <td colspan=1 rowspan=1 > 713 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Driving Brake Standard Preserved by DCDR Body destroyed by arson 2002 Underframe in use as a flat wagon </td></tr>
<tr> <td colspan=1 rowspan=1 > 714 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=1 > Driving Brake Standard </td></tr>
<tr> <td colspan=1 rowspan=1 > 721 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td><td colspan=1 rowspan=7 > Trailer Standard </td></tr>
<tr> <td colspan=1 rowspan=1 > 722 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td colspan=1 rowspan=1 > 723 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td colspan=1 rowspan=1 > 724 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td colspan=1 rowspan=1 > 725 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td colspan=1 rowspan=1 > 726 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td colspan=1 rowspan=1 > 727 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Scrapped </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 728 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Preserved by DCDR </td><td class="highlighted"  colspan=1 rowspan=1 > Trailer Standard Ex MPD driving trailer </td></tr>
</table>
Question:
Which UTA 70 Class trailer cars were rebuilt as DBSO, and when were they rebuilt, respectively?
Answer:
In 1977, 701 and 703 were rebuilt as Driving Brake Standard.